The three of you who are still reading this or who are seeing this post through the magic of the RSS feed might be interested in the Cosmopolis Lexicon. A Lexicon is a shared world-building exercise created by a really cool guy called Neel Krishnaswami a few years ago.
Click the link above for details on that.
This Lexicon features the superheroes and supervillains of a fictional city called Cosmopolis. The game begins on March 18, 2009 and is open to anyone who's interested.
Check it out.