If this isn't the neatest thing you see today, you spend waaaay too much time on the internet. Henry Chu's Fish Harp is musical instrument/visual art hybrid: when a goldfish swims under a glass, the Fish Harp synthesizes the sound a wet finger would make if you ran it along the rim of the glass. The synthesizer is triggered by motion sensors.
Fish Harp is on display at Musique Plastique in Hong Kong. (Admission is free, if you're in the neighborhood.)