The Chapman stick has been around for more than 25 years. It is basically a guitar synthesizer and can be programmed for just about any sound. More advanced guitar synthesizers have come since then. (Check Bela Fleck and the Flecktones. Their guy uses one to play all their percussion.) You can even get a processor to make your acoustic guitar into a synthesizer. Saw Mark O'Connor demo-ing one once. He was playing an acoustic guitar and what you heard was a pipe organ. Looks like fun, but it's not exactly my interest as an instrument.

Chet