In 2003, after a few months doing mostly music, I gravitated back to graphics programming, which is a much more cerebral activity. When my brain gets tired, I'll do some more music again.
As a programmer, I've always had this lingering fantasy that if I were really smart (or lucky), I could write a really simple program that could, thru a series of self-mutations, evolve into a sentient being. Unfortunately, although I've written millions of lines of code, I've never hit on the right combination.
Years ago, a really smart programmer named Karl Sims, an early employee of Danny Hillis, wrote a really cool program that comes as close as anything I've seen to fulfilling that fantasy. His program evolves virtual creatures and was used to produce a series of demonstration videos of his "blocky" creatures, which you may have seen.
I've made a few forays into this area, mostly to produce designs and 2D art. The two most interesting where one that produces 2d patterns, and one that produces crop-circle designs.