Here's a little device that turns almost anything into a touchpad. The video demonstrates various ingenuities such as a banana spacebar and piano stairs. I can foresee that this will be yet another item that I will end up purchasing- just to be used once or twice and then stored away neatly on my ikea shelf (which at least has turned out to be one of the most invaluable purchases yet). But such makeymakey amazingness can't be resisted, can it? Here's the link to their site in case you have the buying bug too.