I'm not sure how this works or why you'd want this but there is a guy who is developing a computer interface that is essentially a tub of mud with sensors at the bottom:
http://dirtycomputing.com/I didn't get a good speed out of the video and the website doesn't tell you very much! Maybe you could teach your pigs to write novels or computer programs?
Another website says he's got a grid of pressure sensors hooked to a Macbook Pro:
http://hackaday.com/2009/05/11/mud-tub-a-t...uter-interface/
