I just came across this site and I must say its simple but good. I've had a play on it and so has my mother - especially pressing number 9 on your keyboard.
If you don't know what I'm taking about, then its a page on a website called Mister Tweak-a-Thon and it's a small flash based application that interacts with the keys you press on your keyboard. For example pressing number 1 will pump his muscle on his arm. The instructions are on the site so go ahead and have a play. I bet you click number 9 more than once or hum a dodgy tune while pressing the keys.