Besides the online gallery, OTIS sponsors many collaborative projects, known as Synergy events. They have included Synergy:Arcana (collaborative Tarot deck; see below) and Synergy:panic! (here is the irc log of the first synergy, recorded live to the web).
For info on OTIS, check out the readme files in these directories.
Nice home page for OTIS Crosswire collaborative project
Ranjit's OTIS Arcana project page
Hey, the OTIS panic! stuff is happening all the time now (more or less). Also, check out the action from last week as well.