Coin Sampler
Thiago has created a Coin Sampler, basically a loop based synthesizer that is programmed by moving coins on a rotating turntable. As each coin passes under an IR sensor, it triggers the playing of a particular sound.
Addendum: Check out what this MIT guy did with two turntables and a similar idea.
I recall burning three or four weeks of a sabbatical getting Saccade.com on the air with Wordpress. So much tweaking…