Document templates
Although not reference material, perhaps these document templates will be useful. Additional template resources are listed at http://tug.org/interest.html#latextemplates.

beamer template
The beamer class creates presentation slides. It has a vast array of features, but here is a basic template:

\documentclass{beamer}

\title{Beamer Class template}
\author{Alex Author}
\date{July 31, 2007}

\begin{document}

\maketitle

% without [fragile], any {verbatim} code gets mysterious errors.
\begin{frame}[fragile]
 \frametitle{First Slide}

\begin{verbatim}
  This is \verbatim!
\end{verbatim}

\end{frame}

\end{document}

One web resource for this: http://robjhyndman.com/hyndsight/beamer/.

book template

\documentclass{book}
\title{Book Class Template}
\author{Alex Author}

\begin{document}
\maketitle

\chapter{First}
Some text.

\chapter{Second}
Some other text.

\section{A subtopic}
The end.
\end{document}

tugboat template
TUGboat is the journal of the TeX Users Group, http://tug.org/TUGboat.

\documentclass{ltugboat}
\usepackage{graphicx}
\usepackage{ifpdf}
\ifpdf
\usepackage[breaklinks,hidelinks]{hyperref}
\else
\usepackage{url}
\fi

\title{Example \TUB\ article}

% repeat info for each author.
\author{First Last}
\address{Street Address \\ Town, Postal \\ Country}
\netaddress{user (at) example dot org}
\personalURL{http://example.org/~user/}

\begin{document}

\maketitle

\begin{abstract}
This is an example article for \TUB{}.
\end{abstract}

\section{Introduction}

This is an example article for \TUB, from
\url{http://tug.org/TUGboat/location.html}.

We recommend the \texttt{graphicx} package for image inclusions, and the
\texttt{hyperref} package for active urls in the \acro{PDF} output.
Nowadays \TUB\ is produced using \acro{PDF} files exclusively.

The \texttt{ltugboat} class provides these abbreviations and many more:

% verbatim blocks are often better in \small
\begin{verbatim}[\small]
\AllTeX \AMS \AmS \AmSLaTeX \AmSTeX \aw \AW
\BibTeX \CTAN \DTD \HTML
\ISBN \ISSN \LaTeXe
\Mc \mf \MFB \mtex \PCTeX \pcTeX
\PiC \PiCTeX \plain \POBox \PS
\SC \SGML \SliTeX \TANGLE \TB \TP
\TUB \TUG \tug
\UG \UNIX \VAX \XeT \WEB \WEAVE

\Dash \dash \vellipsis \bull \cents \Dag
\careof \thinskip

\acro{FRED} -> {\small[er] fred}  % please use!
\cs{fred}   -> \fred
\env{fred}  -> \begin{fred}
\meta{fred} -> <fred>
\nth{n}     -> 1st, 2nd, ...
\sfrac{3/4} -> 3/4
\booktitle{Book of Fred}
\end{verbatim}

For more information, see the ltubguid document at:
\url{http://mirror.ctan.org/macros/latex/contrib/tugboat}
(we recommend using \verb|mirror.ctan.org| for \CTAN\ references).

Email \verb|tugboat@tug.org| if problems or questions.

\bibliographystyle{plain}  % we recommend the plain bibliography style
\nocite{book-minimal}      % just making the bibliography non-empty
\bibliography{xampl}       % xampl.bib comes with BibTeX

\makesignature
\end{document}