The Experimental Gameplay Workshop has posted its 2007 Call for Participation. Jonathan Blow says,
The Experimental Gameplay Workshop is a concentrated mini-conference that happens yearly at the GDC. If you’re working on an innovative / experimental / original game, we encourage you to check out the web site and submit your work.
Some of the games from past years have been really very cool, so to all you developers and designers out there — go submit.