http://www.emacswiki.org/
This wiki collects elisp code, questions and answers related to elisp code and style, introductions to elisp packages and links to their sources, complete manuals or documentation fragments, comments on Emacs and XEmacs features, differences and history, ports, jokes, pointers to clones and emacs-look-alikes, as well as references to other emacs related information on the web.
Alternatively, you might be looking for
EmacsWikiMode or
WikiMode.
(Note that "emacs-wiki" is the name of the
DebianGnuLinux package which installs
EmacsWikiMode for emacs.)
CategoryEmacs CategoryWikiForum