There's a lot of documentation, tutorials, etc. out there that was not written by the LaTeX team themselves. We've started a list pointing to some of it (the order is fairly arbitrary and no indication of quality).
If you know about a great resource for TeX and related documentation not listed here, please contact us.
UK TeX Users Group’s FAQ
The Visual LaTeX FAQ by Scott Pakin is a PDF document presenting examples of customized LaTeX formatting and formatting problems, hyperlinked to appropriate pages in the UK TUG FAQ.
A Visual LaTeX FAQ
Having trouble finding the answer to a LaTeX question? The Visual LaTeX FAQ is an innovative new search interface that presents over a hundred typeset samples of frequently requested document formatting. Simply click on a hyperlinked piece of text and the Visual LaTeX FAQ will send your Web browser to the appropriate page in the UK TeX FAQ. By Scott Pakin.
Question and Answer Websites
TeX - LaTeX Stack Exchange
Stack Exchange is a question and answer site for users of TeX, LaTeX, ConTeXt, and related typesetting systems.
An active community with a lot of LaTeX knowledge available.
TeX und LaTeX, Fragen und Antworten. (German)
Video tutorials on various LaTeX topics
This channel shows a growing collection of high-quality video tutorials from the folks from ShareLaTeX (an online editor for LaTeX) on different aspects of LaTeX, currently a beginners series, a series on Thesis writing, a series on beamer, and one on TikZ. The tutorials are not specific to the editor, so they are worth watching by anybody who wants to get a first impression on a particular topic. Of course, video tutorials can never address all aspects, but these have enough detail to get you started.
If you can’t find what you need in any of the links above, try a search of past postings to the Usenet news group comp.text.tex. One place where you can do that is Google Groups. If you are still puzzled, try posting to comp.text.tex. It’s a friendly group.