At Toronto Music Hack Day I built a simple, yet sleek grid based interface to generate music with cellular automatons. Tap on the grid to add more atoms.
http://tap-pad.herokuapp.com
It's rather beautiful as although the music is random sounding, it's actually 100% deterministic.
I made a web version and an iPad app. You can also share the state of the grid and share it via link:
http://tap-pad.herokuapp.com/661621
Code is all open-sourced on Github under MIT:
https://github.com/dmitric/tap-pad-web
https://github.com/dmitric/tap-pad-ios