Gijs made this really nice synthesizer that sounds great. Make sure to check out the website, because it has a lot of photos, videos and MP3′s of the synth in action.

It started out as a experiment to make a DSP with a atmel using the arduino language.. But the sound quality was kind of low.. so then I changed directions to make it more into a synthesizer.
It uses lookup tables, to generate its sound.
I never used lookup tables before.. So i generated my lookup tables with PHP, and it seems to be working fine.

The Hardware & Software Synhesizer