Dr. Richard Boulanger, of Csound fame, entered into mobile computer music earlier this year with csGrain.
csGrain is a stereo granular sound processor with 10 post-processing effects – all realized through a single Csound orchestra that is rendering, processing, sampling, resampling, synthesizing, resynthesizing, playing, reversing, delaying, triggering, gating, compressing, limiting, chorusing, flanging, echoing, filtering, pitch-shifting, harmonizing, granulizing, and recording – in any combination, or simultaneously; all in real-time, and all 100% being done in cSound!
Not only is it a fun instrument, but the manual also provides links to the respective cSound opcode documentation. Touching the .csd button reveals the source for the orchesetra. It's a clever app offering both interactive sound experimentation as well as computer music fundamentals.