An acquaintance of mine Manuel has been doing some crazy stuff  lately with midi. He recently built a "mididuino" which is an AVR based midi controller running the Arduino Software so that its super easy to program for non-nerds.  If none of that made sense, it is a midi controller that lets you easily make things like polyrhythmic sequencers based on the euclidean algorithm. (huh?) well, the theory of all music having mathematical formulas that govern their rhythms doesn't let you listen to Dancehall the same again. (Godfried Toussaint's paper called "The Euclidean Algorithm Generates Traditional Musical Rhythms" talks about this) Manuel is starting to do some cool things with generating sculptures and graphics from music too so his site is chock full of cool things these days.