In answer to the question Creating a titlepage ^[1], Harish Kumar and azetina provided the following nice title page:

\documentclass[12pt,demo]{report} %% Remove demo in your file.
\usepackage{geometry}
\usepackage{xcolor}
\usepackage{graphicx}
\usepackage{lipsum}% Used for dummy text.
\definecolor{titlepagecolor}{cmyk}{1,.60,0,.40}
\definecolor{namecolor}{cmyk}{1,.50,0,.10} 
%-----------------------------------------------------------------
\begin{document}
% ----------------------------------------------------------------
\begin{titlepage}
\newgeometry{left=7.5cm} %defines the geometry for the titlepage
\pagecolor{titlepagecolor}
\noindent
\includegraphics[width=2cm]{logo.jpg}\\[-1em]
\color{white}
\makebox[0pt][l]{\rule{1.3\textwidth}{1pt}}
\par
\noindent
\textbf{\textsf{UniversitätsKlinikum}} \textcolor{namecolor}{\textsf{Heidelberg}}
\vfill
\noindent
{\huge \textsf{Handbuch 1.3}}
\vskip\baselineskip
\noindent
\textsf{August 2008}
\end{titlepage}
\restoregeometry % restores the geometry
\nopagecolor% Use this to restore the color pages to white
% ----------------------------------------------------------------
\lipsum[1-9]
\end{document}

Here is another example:

\documentclass[letterpaper]{article}
\usepackage{geometry}
\usepackage{xcolor}
\usepackage{amsmath}
\usepackage[some]{background}
\usepackage{lipsum}

\definecolor{titlepagecolor}{cmyk}{1,.60,0,.40}

\backgroundsetup{
scale=1,
angle=0,
opacity=1,
contents={\begin{tikzpicture}[remember picture,overlay]
 \path [fill=titlepagecolor] (current page.west)rectangle (current page.north east); 
 \draw [color=white, very thick] (5,0)--(5,0.5\paperheight);
\end{tikzpicture}}
}

\makeatletter                   
\def\printauthor{%                  
    {\large \@author}}          
\makeatother

\author{%
    Author 1 name \\
    Department name \\
    \texttt{email1@example.com}\vspace{40pt} \\
    Author 2 name \\
    Department name \\
    \texttt{email2@example.com}
    }

\begin{document}

\begin{titlepage}
\BgThispage
\newgeometry{left=1cm,right=6cm,bottom=2cm}
\vspace*{0.4\textheight}
\noindent
\textcolor{white}{\Huge\textbf{\textsf{Hardy's Theorem}}}
\vspace*{2cm}\par
\noindent
\begin{minipage}{0.35\linewidth}
    \begin{flushright}
        \printauthor
    \end{flushright}
\end{minipage} \hspace{15pt}
%
\begin{minipage}{0.02\linewidth}
    \rule{1pt}{175pt}
\end{minipage} \hspace{-10pt}
%
\begin{minipage}{0.63\linewidth}
\vspace{5pt}
    \begin{abstract} 
An abstract is a brief summary of a research article, thesis, review, conference proceeding or any in-depth analysis of a particular subject or discipline, and is often used to help the reader quickly ascertain the paper's purpose. When used, an abstract always appears at the beginning of a manuscript, acting as the point-of-entry for any given scientific paper or patent application. Abstracting and indexing services for various academic disciplines are aimed at compiling a body of literature for that particular subject.
    \end{abstract}
\end{minipage}
\end{titlepage}
\restoregeometry
\lipsum[1-2]
\end{document}

Yet another flavor:

\documentclass[letterpaper]{article}
\usepackage{geometry}
\usepackage{xcolor}
\usepackage{amsmath}
\usepackage[some]{background}
\usepackage{lipsum}

\definecolor{titlepagecolor}{cmyk}{1,.60,0,.40}

\DeclareFixedFont{\bigsf}{T1}{phv}{b}{n}{1.5cm}

\backgroundsetup{
scale=1,
angle=0,
opacity=1,
contents={\begin{tikzpicture}[remember picture,overlay]
 \path [fill=titlepagecolor] (-0.5\paperwidth,5) rectangle (0.5\paperwidth,10);  
\end{tikzpicture}}
}
\makeatletter                       
\def\printauthor{%                  
    {\large \@author}}              
\makeatother
\author{%
    Author 1 name \\
    Department name \\
    \texttt{email1@example.com}\vspace{40pt} \\
    Author 2 name \\
    Department name \\
    \texttt{email2@example.com}
    }
\begin{document}
\begin{titlepage}
\BgThispage
\newgeometry{left=1cm,right=4cm}
\vspace*{2cm}
\noindent
\textcolor{white}{\bigsf Hardy's Theorem}
\vspace*{2.5cm}\par
\noindent
\begin{minipage}{0.35\linewidth}
    \begin{flushright}
        \printauthor
    \end{flushright}
\end{minipage} \hspace{15pt}
%
\begin{minipage}{0.02\linewidth}
    \rule{1pt}{175pt}
\end{minipage} \hspace{-10pt}
%
\begin{minipage}{0.6\linewidth}
\vspace{5pt}
    \begin{abstract} 
An abstract is a brief summary of a research article, thesis, review, conference proceeding or any in-depth analysis of a particular subject or discipline, and is often used to help the reader quickly ascertain the paper's purpose. When used, an abstract always appears at the beginning of a manuscript, acting as the point-of-entry for any given scientific paper or patent application. Abstracting and indexing services for various academic disciplines are aimed at compiling a body of literature for that particular subject.
    \end{abstract}
\end{minipage}
\end{titlepage}
\restoregeometry
\lipsum[1-2]
\end{document}

Yet another example (using code from Trying to do graphical decorations in "ClassicThesis style" ^[2]):

\documentclass[letterpaper]{article}
\usepackage{amsmath}
\usepackage{tikz}
\usepackage{epigraph}
\usepackage{lipsum}

\renewcommand\epigraphflush{flushright}
\renewcommand\epigraphsize{\normalsize}
\setlength\epigraphwidth{0.7\textwidth}

\definecolor{titlepagecolor}{cmyk}{1,.60,0,.40}

\DeclareFixedFont{\titlefont}{T1}{ppl}{b}{it}{0.5in}

\makeatletter                       
\def\printauthor{%                  
    {\large \@author}}              
\makeatother
\author{%
    Author 1 name \\
    Department name \\
    \texttt{email1@example.com}\vspace{20pt} \\
    Author 2 name \\
    Department name \\
    \texttt{email2@example.com}
    }

% The following code is borrowed from: https://tex.stackexchange.com/a/86310/10898

\newcommand\titlepagedecoration{%
\begin{tikzpicture}[remember picture,overlay,shorten >= -10pt]

\coordinate (aux1) at ([yshift=-15pt]current page.north east);
\coordinate (aux2) at ([yshift=-410pt]current page.north east);
\coordinate (aux3) at ([xshift=-4.5cm]current page.north east);
\coordinate (aux4) at ([yshift=-150pt]current page.north east);

\begin{scope}[titlepagecolor!40,line width=12pt,rounded corners=12pt]
\draw
  (aux1) -- coordinate (a)
  ++(225:5) --
  ++(-45:5.1) coordinate (b);
\draw[shorten <= -10pt]
  (aux3) --
  (a) --
  (aux1);
\draw[opacity=0.6,titlepagecolor,shorten <= -10pt]
  (b) --
  ++(225:2.2) --
  ++(-45:2.2);
\end{scope}
\draw[titlepagecolor,line width=8pt,rounded corners=8pt,shorten <= -10pt]
  (aux4) --
  ++(225:0.8) --
  ++(-45:0.8);
\begin{scope}[titlepagecolor!70,line width=6pt,rounded corners=8pt]
\draw[shorten <= -10pt]
  (aux2) --
  ++(225:3) coordinate[pos=0.45] (c) --
  ++(-45:3.1);
\draw
  (aux2) --
  (c) --
  ++(135:2.5) --
  ++(45:2.5) --
  ++(-45:2.5) coordinate[pos=0.3] (d);   
\draw 
  (d) -- +(45:1);
\end{scope}
\end{tikzpicture}%
}

\begin{document}
\begin{titlepage}

\noindent
\titlefont Hardy's Theorem\par
\epigraph{Pure mathematics is on the whole distinctly more useful than applied. For what is useful above all is technique, and mathematical technique is taught mainly through pure mathematics.}%
{\textit{London 1941}\\ \textsc{G. H. Hardy}}
\null\vfill
\vspace*{1cm}
\noindent
\hfill
\begin{minipage}{0.35\linewidth}
    \begin{flushright}
        \printauthor
    \end{flushright}
\end{minipage}
%
\begin{minipage}{0.02\linewidth}
    \rule{1pt}{125pt}
\end{minipage}
\titlepagedecoration
\end{titlepage}
\lipsum[1-2]
\end{document}

You can find other examples at: http://www.latextemplates.com/cat/title-pages

The question LaTeX3 and pauper's coffins ^[1] discusses various ways to implement a famous title page by Tschichold in LaTeX:

The picture above shows the various relationships that this design implements (the arrows are overlayed on a picture of the original).

The implementation (using expl3's coffin concepts) is given in Is there no easier way to float objects and set margins? ^[2]. The LaTeX3 reimplementation then gives this (without trying to use exactly the same fonts):

I find the titlepages of the ConTeXt manuals to be visually very pleasing. A few of them involve randomized elements. The source for some of the manuals is available at this svn mirror ^[1].

(Click on the images to see a bigger version)

My humble contribution- I made this for the, 'Program Review' that we have at our college. The background image it uses can be found here ^[1], but of course you'll probably want to insert your own :)

The code uses the tcolorbox ^[2] and eso-pic ^[3] packages.

% arara: pdflatex
% !arara: indent: {overwrite: yes}
\documentclass{article}
\usepackage[margin=0.5cm,bottom=2cm]{geometry}
\usepackage{kpfonts}
\usepackage{eso-pic}                
\usepackage{tcolorbox}

\tcbuselibrary{skins}

\tcbset{
    pccstyle/.style={
        enhanced,flushright upper,
        boxrule=1.4pt,
        colback=white,colframe=black!50!yellow,
        drop fuzzy midday shadow=black!50!yellow
    }
}

\AddToShipoutPicture{% from package eso-pic: put something to the background
    \AtPageCenter{% start the bar at the bottom right of the page
        \put(-\LenToUnit{.465\paperwidth},-\LenToUnit{.4\paperheight}){% move it to the middle
            %{\transparent{.5}{\includegraphics[width=20cm]{50th_mathematicsproof}}}
            \begin{tcolorbox}[pccstyle,left=0mm,top=0mm,bottom=0mm]
                \includegraphics[width=20cm]{50th_mathematicsproof}
            \end{tcolorbox}
        }%
    }%
    \AtPageLowerLeft{% start the bar at the bottom right of the page
        \put(\LenToUnit{\dimexpr\paperwidth-3cm},0){% move it to the top right
            \color{blue}\rule{3cm}{\LenToUnit\paperheight}%
        }%
        \put(\LenToUnit{\dimexpr\paperwidth-2.7cm},\LenToUnit{17cm}){% move it to the top right
            \color{gray}\scalebox{8}{$\sum$}
        }%
        \put(\LenToUnit{\dimexpr\paperwidth-2.5cm},\LenToUnit{12.5cm}){% move it to the top right
            \color{gray}\scalebox{8}{$\int$}
        }%
        \put(\LenToUnit{\dimexpr\paperwidth-2.3cm},\LenToUnit{8.5cm}){% move it to the top right
            \color{gray}\scalebox{8}{$e$}
        }%
        \put(\LenToUnit{\dimexpr\paperwidth-2.7cm},\LenToUnit{5.0cm}){% move it to the top right
            \color{gray}\scalebox{8}{$\pi$}
        }%
        \put(\LenToUnit{\dimexpr\paperwidth-2.2cm},\LenToUnit{1.5cm}){% move it to the top right
            \color{gray}\scalebox{8}{$i$}
        }%
    }%
}

\pagestyle{empty}
\begin{document}

\vspace*{1cm}
\mbox{}\hfill\scalebox{2}{
    \begin{tcolorbox}[pccstyle,width=6.8cm]
        {\bfseries\LARGE {Program Review} \par}
        {\large \itshape Mathematics \par}
        {\large Portland Community College }
    \end{tcolorbox}
}

\vfill
\centering

\scalebox{2}{%
    \begin{tcolorbox}[pccstyle,width=4.8cm]
        {\scshape Fall 2008--Spring 2013}
    \end{tcolorbox}
}
\end{document}

This is an example derived from the document » Some Examples of Title Pages ^[1]«. It is not the most spectacular one but should be a good starting point.

\documentclass[11pt]{report}
\usepackage[T1]{fontenc}

\newlength{\drop}

\begin{document}
  \begin{titlepage}
    \drop=0.1\textheight
    \centering
    \vspace*{\baselineskip}
    \rule{\textwidth}{1.6pt}\vspace*{-\baselineskip}\vspace*{2pt}
    \rule{\textwidth}{0.4pt}\\[\baselineskip]
    {\LARGE CONUNDRUMS\\ AND \\[0.3\baselineskip] PUZZLES}\\[0.2\baselineskip]
    \rule{\textwidth}{0.4pt}\vspace*{-\baselineskip}\vspace{3.2pt}
    \rule{\textwidth}{1.6pt}\\[\baselineskip]
    \scshape
    Selected and Expanded Papers from the Organisation Working Conference on \\
    Enigmas \\
    Location, date from--to\par
    \vspace*{2\baselineskip}
    Edited by \\[\baselineskip]
    {\Large FIRST EDITOR \\ SECOND EDITOR \\ THIRD EDITOR\par}
    {\itshape Organisation \\ Address\par}
    \vfill
    {\scshape year} \\
    {\large THE PUBLISHER}\par
  \end{titlepage}
\end{document}

In opposite to the document I did not define a command but simply put the necessary code into a titlepage ^[2] environment.

The appendix Section A of the document has important information about all necessary stuff for creating the title pages.

This is just my little collaboration. It's not as professional as some examples and the code is far from elegant. So feel free to edit/adapt and improve.

First a more traditional style. Many old books have a title page that look similar to this. I'v used tcolorbox and tikz with calligra ^[1] font just for fancy.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% This template has been done collecting multiple entries from:
% http://tex.stackexchange.com
%
% Author:
% Graciano Bay
%
% License:
% CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/)
%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


\documentclass[b4paper]{memoir}
\usepackage[margin=1.5cm,top=2cm,bottom=2cm]{geometry}
\usepackage[usenames,dvipsnames,svgnames,table]{xcolor}
\usepackage{calligra}
\usepackage{tikz}
\usetikzlibrary{matrix,fit,chains,calc,scopes}            
\usepackage{tcolorbox}
\tcbuselibrary{skins}
\usepackage{auto-pst-pdf} %To compile psvectorian directly
\usepackage{psvectorian}
\renewcommand*{\psvectorianDefaultColor}{Green}%

\tcbset{
    Baystyle/.style={
        sharp corners,
        enhanced,
        boxrule=6pt,
        colframe=OliveGreen,
        height=\textheight,
        width=\textwidth,
        borderline={8pt}{-11pt}{},
    }
}



\pagestyle{empty}
\begin{document}
\centering
    \begin{tcolorbox}[Baystyle,]
        {\begin{center}
        \vspace*{0.14\textheight}
        \fontsize{45}{45}\scshape Book Title\\        
        \vspace*{0.018\textheight}
        \vspace*{0.2\textheight}
        % Big Logo\\
        \vspace*{0.2\textheight}
        {\fontsize{12}{12}\calligra A original story of\\}
        \fontsize{28}{28}\scshape Author Name\\
        \vspace*{0.1\textheight}
        \centering
        \begin{tikzpicture}[
        start chain=main going right,
          ]

             \node[on chain,align=center,draw=none] (a1){{\fontsize{12}{12}\calligra Illustrations by} \\
             {\Large Designer}
             }; 
             { [start branch=A going below]
             \node[on chain,align=center,draw=none,scale=0.01](d1){};
             \node[on chain,align=center,draw=none,](d2){\Huge Press logo};
             %\node[on chain,align=center,draw=none,scale=0.01](d3){};
             }
             \node[on chain,align=center,draw=none] (a2){\psvectorian[]{148}}; 
             { [start branch=B going below]
             \node[on chain,align=center,draw=none,scale=0.01](s1){};
             \node[on chain,align=center,draw=none,](s2){};
             %\node[on chain,align=center,draw=none,scale=0.01](s3){}; 
             }
             \node[on chain,align=center,draw=none]  (a3){{\fontsize{12}{12}\calligra Final review by} \\
             {\Large Revisor}
             };          
             { [start branch=C going below]
             \node[on chain,align=center,draw=none,scale=0.01](e1){};
             \node[on chain,align=center,draw=none,](e2){\Huge Other Logo};
             %\node[on chain,align=center,draw=none,scale=0.01](e3){}; 
        }
        \draw[black] (s2.north) -- (s2.south);
        \end{tikzpicture}
            \end{center}}
    \end{tcolorbox}
\end{document}

My second is certainly not classic looking. Here i've used only tikz.

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%
% This template has been done collecting multiple entries from:
% http://tex.stackexchange.com
%
% Author:
% Graciano Bay
%
% License:
% CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/)
% 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%


\documentclass[b4paper]{memoir}
\usepackage[margin=1cm,]{geometry}
\usepackage[scaled]{helvet}
\usepackage[usenames,dvipsnames,svgnames,table]{xcolor}
%\setlength{\parindent}{0pt}
\usepackage{tikz}   
\usetikzlibrary{calc,scopes,positioning,backgrounds}            
\usepackage{lipsum}
\usepackage{microtype}
\pagestyle{empty}
\begin{document}
        \begin{tikzpicture}[local bounding box=picture, baseline=(picture.south)] 
        \node [draw=none] (A) at (0,0) {};
        \node [draw=none] (B) at (15,5) {};
        \node [draw=none] (C) at (5,-5) {};
        \foreach \s/\col in {1.5/ProcessBlue, 1/SkyBlue, 0/ProcessBlue}{
          \path [draw,\col, line width=40] ($(A.west)-(0,\s cm)$) to ($(C.west)-(0,\s cm)$) to ($(B.west)-(0,\s cm)$);
        }
        %
        \node [draw=none] (A2) at (0,-20) {};
                \node [draw=none] (B2) at (22,-8) {};
                \node [draw=none] (C2) at (5,-25) {};
                \foreach \s/\col in {1.5/ProcessBlue!20!white, 1/SkyBlue!20!white, 0/ProcessBlue!20!white}{
                \path [draw,\col, line width=40] ($(A2.west)-(0,\s cm)$) to ($(C2.west)-(0,\s cm)$) to ($(B2.west)-(0,\s cm)$);
         } 
        %        
        \node [draw=none,text width=\textwidth/1.7] (T1) at (10,0) {\fontsize{50}{50}\MakeUppercase{\textsf{\textbf{A Book Title}}}};
        %
        \node [draw=none,text width=\textwidth/1.7] (T2) at (10,-14) {
        \fontsize{20}{20}\textsf{\textbf{\textcolor{ProcessBlue}{Subtitle}}}\\
        \vspace*{0.02\textheight}
        \LARGE{\lipsum[1]}        
        };
        %
        \end{tikzpicture}
\end{document}

From my master's thesis. In the background one can see some (dirty) nanoparticles

Code:

\titlehead{%
\tikzexternaldisable
\begin{tikzpicture}[remember picture,overlay]
\node[inner sep=0,opacity=1] at (current page.center) {\includegraphics[height=\paperheight]{bgtitle.jpg}};
\begin{scope}
        %\path[clip,decoration={random steps, segment length=6pt, amplitude=2pt},
            %decorate] ($(current page.south west)+(5.1,6)$) -- ++(9,0) -- ++ (0,2) -- ++ (-1.5,4) -- ++ (0.5,2) -- ++ (-0.35,2) -- ++ (1,1) -- ++ (3.5,0.5) -- ++ (0,5) -- ++ (-4.75,0) -- ++ (-0.5,0.75) -- ++ (-4.25,0) -- ++ (-0.25,0.25) -- ++ (0,2) -- ++(-5.25,0) -- ++ (0,-8.25) -- ++ (0.25,-0.25) -- ++ (4,0) -- ++ (0.5,-0.75) -- ++ (-0.35,-2) -- ++ (0.5,-2) -- ++ (-2,-4) -- cycle;
            \path[clip,decoration={random steps, segment length=6pt, amplitude=2pt},
            decorate] ($(current page.south west)+(5.1,5)$) -- ++(12.15,0) -- ++ (0,12.5) -- ++ (0,5) -- ++ (-4.75,0) -- ++ (-0.5,0.75) -- ++ (-4.25,0) -- ++ (-0.25,0.25) -- ++ (0,2) -- ++(-5.25,0) -- ++ (0,-8.25) -- ++ (0,-12.15) -- cycle;
\draw[fill=white,inner sep=0,opacity=0.5] (current page.south west) rectangle (current page.north east);
\end{scope}
\end{tikzpicture}%
\tikzexternalenable
\addfontfeatures{Numbers=Lining}%
  {University of YourTown\\
   Physics Department\\
   Physics Institute
   }}
\subject{\textit{\textbf{aster's esis}}\vspace*{-1cm}}
\publishers{\vspace{0.7cm}\addfontfeatures{Numbers=Lining}\large \begin{minipage}{0.6\textwidth}
                         \indent\newlength{\titlepagenewlengthup}\setlength{\titlepagenewlengthup}{\widthof{1 }}\hphantom{2ⁿ }\hspace*{-\titlepagenewlengthup}1 supervisor: Professor Doctor Doe\\
                        2ⁿ supervisor: Professor Doctor Doe\\
                         \newlength{\titlepagenewlength}\setlength{\titlepagenewlength}{\widthof{ad}}\hphantom{2ⁿ super}\hspace*{-\titlepagenewlength}advisor: Doctor Doe\end{minipage}\vspace*{-0.7cm}}
\author{Max Mustermann}
\title{%
    \vspace{0.3cm}%
    \hrule height 2pt%
    \vspace{0.3cm} Title of thesis%
    \vspace{0.3cm}%
    \hrule height 2pt%
    \vspace{0.3cm}}
\subtitle{\vspace*{1.0cm}\includegraphics{Logo1}}
\date{\today}

I have few examples to show. You can download these from Here ^[1], Here ^[2], Here ^[3], and Here ^[4]. These are originally Peter Wilson's titlepage examples that I have changed the examples little to work with xepersian ^[5] package to typeset Persian documents.

Several examples from the 4th archive:

1

3

5

Hope it's OK to share my own example – the title page I created, inspired by this very thread, for notes I took in an algebraic geometry class ^[1] a few years back.

TeX source:

\documentclass{amsart}
\usepackage[margin=1in]{geometry}
\usepackage{afterpage}
\usepackage{tikz}
\usetikzlibrary{fadings}

\begin{document}

\DeclareFixedFont{\titlefont}{T1}{ppl}{b}{}{0.7in}
\DeclareFixedFont{\subtitlefont}{T1}{ppl}{b}{}{0.4in}
\afterpage{\restoregeometry}
\newgeometry{left=1in, right=1in,top=1in, bottom=0in}
\definecolor{mytan}{HTML}{F6D5A8}
\pagecolor{mytan}\afterpage{\nopagecolor}

\thispagestyle{empty}
\begin{flushright}
\titlefont Algebraic Geometry\\
\subtitlefont UT Austin, Spring 2016
\end{flushright}
\vfill
\begin{center}
\begin{tikzpicture}
\node[scope fading=north, inner sep=0pt, outer sep=0pt]{
 \makebox[\textwidth]{\includegraphics[width=\paperwidth]{../the-great-wave-off-kanagawa}}
};
\end{tikzpicture}
\end{center}

% for additional pages after the title, uncomment the following line first:
% \clearpage

\end{document}

For my school (something decent):

\documentclass{article}
\usepackage{tikz,fouriernc}
\usetikzlibrary{calc}
\definecolor{lime}{RGB}{0,0,128}
\begin{document}
    \begin{titlepage}
        \begin{tikzpicture}[overlay,remember picture]
            \fill[lime!10] (current page.south east) rectangle (current page.north west);
            \fill[lime,even odd rule] (current page.south west) rectangle ([xshift=1.5cm]current page.north west) ($(current page.north west)!.5!(current page.south west)$) arc(180:270:3) ($(current page.north west)!.5!(current page.south west)$) arc(270:450:3.5) ([yshift=7cm]$(current page.north west)!.5!(current page.south west)$)  arc(180:90:3);
%           \draw[lime!10,double=lime!10,double distance=2mm] (current page.south west) --+ (2,2) --+ (-2,6) --+ (2,8) --+ (-2,9) --+ (2,13) --+ (-2,18) --+ (2,30);
                \draw[lime,thin] (13,-1) node[lime,above left] {\Huge\it Teacher} --+ (0,3) node[lime,below right] {\Huge Q11};
            \node[yshift=-5cm,xslant=1,yscale=1.6,lime!40,opacity=.2] at (9.5,-6.5) {\scalebox{6}{Mathematik}};
            \node[yshift=-5cm,lime] at (8,-7) {\scalebox{6}{Mathematik}};
                \draw[lime,fill=lime!20] ([xshift=-1cm]current page.north east) -- ([yshift=-1cm]current page.north east) -- ([yshift=-2cm]current page.north east) -- ([xshift=-2cm]current page.north east);
            \path ([xshift=-1cm]current page.north east) -- ([yshift=-1cm]current page.north east) node[midway,sloped,below=.1cm,lime] {My Name};
        \end{tikzpicture}
    \end{titlepage}
\end{document}

Here is the output:

I used Harish Kumar and azetina code and add this falling dominos picture from tikz example (http://www.texample.net/tikz/examples/dominoes/):

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                               PREAMBLE
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\documentclass[11pt,a4paper]{report}
\usepackage{tikz}
\usepackage{amsmath}
\usepackage{epigraph}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                            Cover Page Details
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%    
\usetikzlibrary{calc}
\tikzset{3D/.cd,
  x/.store in=\xx, x=0,
  y/.store in=\yy, y=0,
  z/.store in=\zz, z=0
}

\tikzdeclarecoordinatesystem{3D}{%
  \tikzset{3D/.cd,#1}%
  \pgfpoint{sin(\yy)*(\xx)}{-((\xx)/75)^2+(\zz)/100*(\xx)}%
}
\renewcommand\epigraphflush{flushright}
\renewcommand\epigraphsize{\normalsize}
\setlength\epigraphwidth{0.7\textwidth}
\definecolor{titlepagecolor}{cmyk}{1,.60,0,.40}
\DeclareFixedFont{\titlefont}{T1}{ppl}{b}{it}{0.5in}
\makeatletter                       
\def\printauthor{%                  
    {\large \@author}}              
\makeatother
\author{%
    Author Names \\  %%%% Your Name
    Department \\    %%%% Department Name
    \texttt{Email Address}\vspace{5pt} \\ %%% Your Email Address
    }
\newcommand\titlepagedecoration{%
\begin{tikzpicture}[line join=round, very thin]
  \def\e{1260}
  \foreach \x [evaluate={\i=mod(\x+90,360); \j=int((\i<180)*2-1); \t=3;
    \sc=\x/\e; \n=int((\e-\x)/15+5); \X=\x/\e;}] in {10,25,...,\e} {

    \path [shift={(3D cs:x=\x-\t,y={3*sin(\x-\t)})}, yslant=cos(\x)/5]
      (-\X/2, 0)   coordinate (A')  ( \X/2, 0)   coordinate (B')
      ( \X/2,2*\X) coordinate (C')  (-\X/2,2*\X) coordinate (D');

    \path [shift={(3D cs:x=\x,y=3*sin \x)}, yslant=cos(\x)/5]
      (-\X/2, 0)   coordinate (A) ( \X/2, 0)   coordinate (B)
      ( \X/2,2*\X) coordinate (C) (-\X/2,2*\X) coordinate (D);

    \filldraw [black!90] (B) -- (B') -- (C') -- (C)  -- cycle;
    \filldraw [black!80] (A) -- (A') -- (D') -- (D)  -- cycle;
    \filldraw [black!70] (C) -- (D)  -- (D') -- (C') -- cycle;
    \filldraw [black]    (A) -- (B)  -- (C)  -- (D)  -- cycle;

    \node [text=white, shift={($(C)!0.5!(D)$)}, anchor=north,
      yslant=cos(\x)/5, font=\sf, scale=\sc*1.5] at (0,-.33*\X) {\n};
  }
  %
  \foreach \i [evaluate={\x=\i*30-10; \X=1; \n=int(5-\i); \xsl=\x/180}]
    in {1,...,4} {

    \path [shift={(3D cs:x=\x+\e,y=-3*\x/90)}, yslant=cos \e/5, xslant=\xsl]
      (-\X/2, 0)           coordinate (A) ( \X/2, 0)           coordinate (B)
      ( \X/2, \X*2-\x/360) coordinate (C) (-\X/2, \X*2-\x/360) coordinate (D);

    \path [shift={(3D cs:x=\x+\e,y=-3*\x/90)}, shift={(5/50,5/50-\i*2/50)},
      yslant=cos \e/5, xslant=\xsl]
      (-\X/2, 0)           coordinate (A') ( \X/2, 0)           coordinate (B')
      ( \X/2, \X*2-\x/330) coordinate (C') (-\X/2, \X*2-\x/330) coordinate (D');

    \filldraw [black!70] (C) -- (D)  -- (D') -- (C') -- cycle;
    \filldraw [black!70] (A) -- (B)  -- (B') -- (A') -- cycle;
    \filldraw [black!90] (B) -- (B') -- (C') -- (C)  -- cycle;
    \filldraw [black]    (A) -- (B)  -- (C)  -- (D)  -- cycle;

    \node [text=white, shift={($(C)!0.5!(D)$)}, anchor=north, xslant=\xsl,
      yslant=cos \e/5, font=\sf, scale=1.5] at (0,-.33*\X) {\n};
  }
\end{tikzpicture}
}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                               COVER
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%    
\begin{document}
\begin{titlepage}
\noindent
\titlefont Chapter 1\par
\epigraph{Pure mathematics is on the whole distinctly more useful than applied. For what is useful above all is technique, and mathematical technique is taught mainly through pure mathematics.}%
{\textit{London 1941}\\ \textsc{G. H. Hardy}}
\null\vfill
\vspace*{1cm}
\noindent
\hfill
\begin{minipage}{0.35\linewidth}
    \begin{flushright}
        \printauthor
    \end{flushright}
\end{minipage}
%
\begin{minipage}{0.02\linewidth}
    \rule{1pt}{60pt}
\end{minipage}
\titlepagedecoration
\end{titlepage}
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%                            START HERE
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\section{Test}
This is a test. 
\[
\pi \approx 3.14159 26535 89793 23846  \]
    \[
        e=2+\cfrac{1}
          {1+\cfrac{1}
          {2+\cfrac{1}
          {1+\cfrac{1}
          {1+\cfrac{1}
          {4+\cfrac{1}
          {1+\cfrac{1}
          {1+\cfrac{1}
          {6+\cdots}}}}}}}}
    \]
\end{document}

which will produce this

Not a really funcy one but it is nice. I used this ^[1] post. Of course all the colours, the language and the font size can change.

\documentclass[14pt]{extbook}
\usepackage[utf8]{inputenc}
\usepackage{parcolumns}
\usepackage[english, greek]{babel}
\usepackage{color}

\usepackage[T1]{fontenc}
\usepackage{pagecolor}
\usepackage{xcolor}
\usepackage[normalem]{ulem}
\usepackage{graphicx}
\usepackage{titlesec,}
\usepackage[series={},nocritical,noend,noeledsec,nofamiliar,noledgroup]{reledmac}
\usepackage{reledpar}


\titleformat{\chapter}
{\flushright\normalfont\LARGE\bfseries\color{burntorange}}{\thechapter}{1em}{}
\titlespacing{\chapter}{-18pt}{-102pt}{10pt}

\titleformat{\section}
{\center\normalfont\large\bfseries\color{amaranth} }{\thesection}{1em}{}

\title{\textit{ \textbf{\textcolor{azure}{\textlatin{TITLE}}}}}
\author{\Large{\bfseries {\textcolor{burntorange}{\textlatin{AUTHOR}}}
        
        \definecolor{burlywood}{rgb}{0.87, 0.72, 0.53}
        
        \usepackage[%
        margin=4cm
        %,showframe% to show the page layout
        ]{geometry}
        \usepackage[object=vectorian]{pgfornament}
        
        \newcommand\om{5mm}% ornament margin
        \newcommand\ow{5cm}% ornament width
        \newcommand\ols{5.5mm}% ornament line shift
        \newcommand\on{63}% ornament number
        \colorlet{bordercolor}{burlywood}
        \tikzset{
            ol/.style={line width=1mm,dotted}% style for the lines
        }
        
        % define the border and save it in a box
        \newsavebox\border
        \sbox\border{%
            \tikz[color=bordercolor]{
                \useasboundingbox(0,0)rectangle(\paperwidth,-\paperheight);
                \foreach[count=\i]\a/\p/\s in {%
                    north west/{\om,-\om}/none,
                    north east/{{\paperwidth-\om},-\om}/v,
                    south east/{{\paperwidth-\om},{-\paperheight+\om}}/c,%
                    south west/{\om,{-\paperheight+\om}}/h%
                }\node[anchor=\a](n\i) at (\p){\pgfornament[width=\ow,symmetry=\s]{\on}};
                \begin{scope}[ol]
                    \draw([yshift=-\ols]n1.north east)--([yshift=-\ols]n2.north west);
                    \draw([xshift=-\ols]n2.south east)--([xshift=-\ols]n3.north east);
                    \draw([yshift=\ols]n3.south west)--([yshift=\ols]n4.south east);
                    \draw([xshift=\ols]n4.north west)--([xshift=\ols]n1.south west);
                \end{scope}
            }%
        }
        
        \usepackage[manualmark]{scrlayer-scrpage}
        \clearpairofpagestyles
        \cfoot*{\pagemark}
        
        % define a switch to enable and disable the border
        \newif\ifBorder
        % define a new layer
        \DeclareNewLayer[{%
            background,
            page,
            contents={\ifBorder\usebox\border\fi}
        }]{border.bg}
        % add the border layer to all layer page styles (scrheadings, plain, empty, ...) ...
        \AddLayersAtBeginOfPageStyle{@everystyle@}{border.bg}
        
        
        
        
        \usepackage{graphics}
        \definecolor{burntorange}{rgb}{0.8, 0.33, 0.0}
        \definecolor{azure}{rgb}{0.0, 0.5, 1.0}
        \definecolor{amaranth}{rgb}{0.9, 0.17, 0.31}
        \definecolor{dg}{rgb}{0.0, 0.0, 1.0}
        \definecolor{dr}{rgb}{1.0, 0.13, 0.32}
        \definecolor{cerulean}{rgb}{0.0, 0.48, 0.65}
        \definecolor{bv}{rgb}{0.8,0.0,0.0}
        \definecolor{buff}{rgb}{0.94, 0.86, 0.51}
        
        \usepackage[colorlinks, unicode]{hyperref}
        \begin{document}
            
            \begin{titlepage}
                \pagecolor{buff}
                \Bordertrue% enable the border
                {\raggedright
                    
                    \begin{minipage}{0.48\textwidth}\raggedright    
                        {\itshape\bfseries\color{burntorange}       \textlatin{INSTITUTION} }
                \end{minipage}}
                \begin{minipage}{0.48\textwidth}\raggedleft
                    {\itshape\bfseries\color{burntorange} \textlatin{SCHOOL}
                }\end{minipage}
                \centering
                %
                
                
                \Large
                \vspace{3cm}
                
                \vspace{2cm}
                
                \rule{\textwidth}{1.6pt}\vspace*{-\baselineskip}\vspace*{2pt}
                \rule{\textwidth}{0.4pt}\\[\baselineskip]
                \vspace{14pt}
                
                {\bfseries
                    \Huge\color{azure}  \itshape
                    \textlatin{TITLE}%
                }
                \\
                
                
                \par
                \rule{\textwidth}{0.4pt}\vspace*{-\baselineskip}\vspace{3.2pt}
                \rule{\textwidth}{1.6pt}\\[\baselineskip]
                \vspace{2cm}
                %ΗΜΕΡΟΜΗΝΙΑ
                {\normalsize \today}
                
            \end{titlepage}
        

        \clearpage
                \Borderfalse% disable the border
                \pagecolor{white}
    
     \end{document}

My cover book (picture and code changed for a typo - thanks CarLaTex!) :

Code:

\documentclass{article}

\usepackage[dvipsnames]{xcolor}
\usepackage{tikz}
\usetikzlibrary{ shapes.geometric }
\usetikzlibrary{calc}
\usepackage{anyfontsize}
\setlength{\parskip}{4cm}
\setlength{\parindent}{-1.5cm}
\begin{document}
    \pagestyle{empty}
    
    \begin{tikzpicture}[remember picture,overlay]
        %%%%%%%%%%%%%%%%%%%% Background %%%%%%%%%%%%%%%%%%%%%%%%
        \fill[blue!50] (current page.south west) rectangle (current page.north east);
        
        
        \foreach \i in {2,...,22}
        {
            \node[rounded corners,blue!2,draw,regular polygon,regular polygon sides=5, minimum size=\i cm,ultra thick] at ($(current page.south)+(0,1)$) {} ;
        }
        
        %%%%%%%%%%%%%%%%%%%% Background Polygon %%%%%%%%%%%%%%%%%%%% 
        \foreach \i in {0,...,15}
        {
            \node[rounded corners,blue!2,draw,regular polygon,regular polygon sides=12, minimum size=\i cm,ultra thick] at ($(current page.west)+(1.5,0)$) {} ;
        }
        \foreach \i in {0,...,15}
    {
        \node[rounded corners,blue!2,draw,regular polygon,regular polygon sides=12, minimum size=\i cm,ultra thick] at ($(current page.east)+(-1.5,0)$) {} ;
    }   
%       \foreach \i in {2,...,22}
%       {
%           \node[rounded corners,blue!2,draw,regular polygon,regular polygon sides=18, minimum size=\i cm,ultra thick] at ($(current page.north)+(0,-4.5)$) {} ;
%       }
        
        
%       \foreach \i in {21,...,6}
%       {
%           \node[cyan!20,rounded corners,draw,regular polygon,regular polygon sides=12, minimum size=\i cm,ultra thick] at ($(current page.south east)+(-0.5,0.45)$) {} ;
%       }
        
        
        %%%%%%%%%%%%%%%%%%%% Title of the Report %%%%%%%%%%%%%%%%%%%% 
        \node[left,white,minimum width=0.625*\paperwidth,minimum height=3cm, rounded corners] at ($(current page.north)+(6.7,-5)$)
        {
            {\fontsize{40}{45} \selectfont \bfseries TRIGONOMETRIA}
        };
        
        %%%%%%%%%%%%%%%%%%%% Subtitle %%%%%%%%%%%%%%%%%%%% 
        \node[left,white,minimum width=0.625*\paperwidth,minimum height=2cm, rounded corners] at ($(current page.north)+(7,-6.2)$)
        {
            {\LARGE \textbf{Per neo docenti di matematica, studenti,  cultori}}
        };
        
        %%%%%%%%%%%%%%%%%%%% Author Name %%%%%%%%%%%%%%%%%%%% 
        \node[left,white,minimum width=0.625*\paperwidth,minimum height=2cm, rounded corners] at ($(current page.north)+(6.7,-3)$)
        {
            {\huge \textbf{Raffaele Santoro}}
        };
    
        %%%%%%%%%%%%%%%%%%%% Year %%%%%%%%%%%%%%%%%%%% 
        \node[rounded corners,fill=blue!10,text =blue,regular polygon,regular polygon sides=5, minimum size=3.5 cm,inner sep=0,ultra thick] at ($(current page.south)+(0,1)$) {
            \includegraphics[scale=.8]{RSEdizioni.png}
        };
        
    \end{tikzpicture}\\

\includegraphics[scale=1]{fg_b.png}
    
\end{document}

I hope you find this at least interesting. The background image is from a website for free images:

Book cover:

It's for my in-progress book. Code:

% !TeX spellcheck = es_ES
% !TeX program = xelatex
\documentclass[12pt,letterpaper,twoside]{book} 
\usepackage{titletoc}       
\usepackage{ucs}                
\usepackage[spanish,es-nodecimaldot]{babel} 
\usepackage{fontspec}       
\usepackage[T1]{fontenc}       
\setsansfont{URWClassico}[
    Path=./URWClassico/,
    Extension = .otf,
    UprightFont=*-Regular,
    BoldFont=*-Bold,
    ItalicFont=*-Italic,
    BoldItalicFont=*-BoldItalic
    ]   
\usepackage{color}
\usepackage{xcolor,colortbl}
    \definecolor{orangy}{RGB}{255,122,4}
    \definecolor{blueish}{RGB}{4,122,255}
    \definecolor{aqua}{RGB}{0,100,150}
    \definecolor{deepblue}{RGB}{0,102,205}
    \definecolor{yellowish}{RGB}{255,255,0}
    \definecolor{chapopcolor}{RGB}{0,100,150}
\usepackage{wallpaper} 
\usepackage[skip=0.4em,indent=1em]{parskip}
    \renewcommand{\baselinestretch}{1.1}   
    \raggedbottom       
\usepackage{graphicx}
    \graphicspath{ {images/} }
\usepackage{tikz}    
    \usetikzlibrary{babel}
    \usetikzlibrary{arrows.meta,calc,positioning,shapes,arrows,decorations.pathmorphing}
    \usetikzlibrary{cd}
\usepackage[left=4cm,right=4cm,top=2.7cm,bottom=2.5cm,outer=3cm,inner=3cm,heightrounded]{geometry}  
\usepackage[breaklinks=true,
colorlinks=true,linkcolor=blue!22!black,urlcolor=blue,citecolor=black,anchorcolor=blue!70!black,
bookmarks=true,pdfpagelayout=TwoPageRight]{hyperref}
\usepackage{tcolorbox}       
\usepackage{varwidth}        
    \tcbuselibrary{breakable,skins,theorems}



\begin{document}
\frontmatter

\begin{titlepage}
\newgeometry{left=7.5cm,top=1.2cm,right=1cm}
\begin{tikzpicture}[remember picture, overlay]
\node[opacity=1,inner sep=0pt] at (current page.center)
{\includegraphics[width=\paperwidth,height=\paperheight]{wall/wall45b}};
\end{tikzpicture}
\vphantom{A}
\vfill
\noindent{\fontsize{70}{48} \selectfont \bfseries\sffamily lógica básica.}
\\{\fontsize{20}{48} \selectfont \bfseries\sffamily una introducción al arte del razonamiento}
\par
\noindent
\makebox[0pt][l]{\rule{1.3\textwidth}{1pt}}
\par
\noindent
{\large\sffamily \href{mailto:}{\bfseries carlos romero}}
\par
\vskip\baselineskip
\noindent \textsf{(versión parcial de \today.)}
\end{titlepage}
\restoregeometry
\pagecolor{white}
\pagestyle{plain}
\end{document}

I can post also code if requested.