The Science Magazine site has a pretty interesting video of what's called robotic music which is interesting for what it reveals about the definition of  a 'robot.' The gadgets you'll see are basically collections of actuators put together in interesting ways to generate different kinds of sounds. They hardly classify as robots in the stricter sense of the word, particularly in that they basically play musical scores created by humans. But the overall effect is worth watching.

http://www.sciencemag.org/cgi/content/full/319/5870/1613b