http://www.engadget.com/2007/03/29/scientists-concoct-a-living-interface/
From the page: “Recently cooked up by a team of German researchers, this interface enlists the services of a tiny critter called a Daphnia, which gets placed under a microscope that tracks its movement as it reacts to various stimuli. That then gets translated into a farily impressive light show (as seen in the video after the break), with the pint-sized subject also apparently composing an accompanying piece of music in the process.”