atomswarm

atomswarm is

"a framework for performance and composition, based on swarming behaviours similar to those seen in flocks of social animals. It can be thought of as a self-organising ecosystem, whose structure is internally regulated by limited resource availability and each agent's pursuit of internal homeostasis.

Sonic behaviours are determined by each agent's genetic disposition, the relationships between agents, and the population's continued evolution over time."

I saw a performance/demo of this software at a conference and was impressed. Whilst it can sometimes be hard to associate the onscreen movements with the generated sound, the majority of the time things do make sense. The output of the system looks and sounds very impressive.
At the website you can find links to video and audio as well as a description of the project along with examples of the code used.
The site also contains info on the developers other projects