Batuhan Bozkurt put together a surprisingly simple set of cellular automaton rules to create music. He calls it Otomata, or online music generative music instrument.
Each alive cell has 4 states: Up, right, down, left. at each cycle, the cells move themselves in the direction of their internal states. If any cell encounters a wall, it triggers a pitched sound whose frequency is determined by the xy position of collision, and the cell reverses its direction. If a cell encounters another cell on its way, it turns itself clockwise.
This set of rules produces chaotic results in some settings, therefore you can end up with never repeating, gradually evolving sequences. Go add some cells, change their orientation by clicking on them, and press play, experiment, have fun.
If you encounter something you like, just press “Copy Piece Link” and save it somewhere, or better, share it!
Otomata playing my favorite piece so far:
[iframe http://www.earslap.com/projectslab/otomata?q=7d5p7s8m4y4i211p1u3s 680 800]
Discussion and great ideas:
From ycombinator news:
[iframe http://news.ycombinator.com/item?id=2454614 680 1000]
[iframe http://www.reddit.com/r/reddit.com/comments/grh8p/reddit_i_made_an_online_audiomusic_toy_to_kill/ 680 1000]