A wiki site devoted to RubyLanguage.
http://wiki.rubygarden.org/Ruby
Unfortunately the above no longer gives the previous content. See http://www.ruby-forum.com/topic/138639 for a discussion of this.
There is an archive at http://web.archive.org/web/*/http://rubygarden.org
This seems to give access to the previous web site: http://web.archive.org/web/20071016094753/www.rubygarden.org/Ruby/page/show/HomePage