This is about 2 years old I guess, and it's not open source. But I just found out about it last night and it's very cool. It's a procedural synthesis engine for writing graphics demos. http://produkkt.abraxas-medien.de/werkkzeug1 I thought the look and feel was vaguely PDish, which led me to wonder if PD is capable of this sort of thing or not (i've never played with GEM).