Narbotic has posted some info on the ArduinoSynth, his first attempt at microcontroller programming.
From Narbotic:
So far it’s a 12-note monophonic synth with transposition selection via one 10K pot. I’m using a gutted toy keyboard for the switches and a simple low pass filter to smooth the output a bit.
Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software. It’s intended for artists, designers, hobbyists, and anyone interested in creating interactive objects or environments.
Link via Make:Blog