Freeduino & Synthesizer combo

The Fluxamasynth is a combination Freeduino (Atmega328 chip) paired with Atmel's ATSAM2195 single-chip MIDI sound system, which is part of their Dream Sound Synthesis line of programmable ICs. It was intended for battery powered keyboards or portable Karaoke machines, but I'm sure you can use and abuse the Fluxamasynth in all sorts of new and interesting ways.

http://shop.moderndevice.com/products/fluxamasynth-rev-1