A Make: Blog reader, garydion, posted this in response to my Making Arduino sing piece:

On the topic of music on microprocessors, be sure to check out this site
where a wavetable synthesizer is programmed into an Atmel ATtiny45.
Amazing! I had to download the code and program a chip to confirm it
really does sound that good. And it does. Enjoy!

Wavetable Melody Generator – Link