pure data can be used for live music performance, sound effects, composition, audio analysis, interfacing with sensors, using cameras, controlling robots or even interacting with websites.
since all of these various media are handled as data within the program, mashups of video, sound, and sensor data are possible.
now available as an android compatible library: pdlib, pure data for android
interestingly, pd (pure data) is used as a procedural music generator in the game spore.
here's a nice rundown post on create digital music.