Context Free: a program that generates images from a grammar.

Structure Synth http://structuresynth.sourceforge.net/ works similarly in 3D. I've used it with SunFlow http://sunflow.sourceforge.net/ to make some pretty neat images relatively easily:

http://www.getdropbox.com/gallery/111770/1/grfx?h=7e3f2e (view full-size for best effect).

Since _why is in the news today, here's an interesting post about a similar context-free graphics generator: http://hackety.org/2008/12/04/theFrustratingMagicalAspect.ht...

(He's also a fan of Context Free, and has written about it elsewhere.)

I've spent many an hour on that and related sites, I've also found that Flickr is a good source for inspiration: http://www.flickr.com/photos/tags/contextfree/interesting/

I got into this a while back. One of my.. things was used for the splash screen.

http://www.contextfreeart.org/gallery/view.php?id=207