Rock Band drums, quite possibly the most awesome gaming peripheral ever. Sadly they have a very annoying flaw in the form of a crappy plastic bass pedal. If you haven't already, you most certainly will break the pedal at some point. And if you're like me, you've managed to break 3 of them in the 4 months that the game has been out.
Put the magnet on the underside of the pedal, use whatever methods you deem necessary to keep it from falling off. Then put the other piece under it, just like it was in the plastic pedal. It'll take some experimenting, but once you get everything positioned correctly the game will register bass hits whenever your real bass pedal hits the practice pad.
Now I can rock the fuck out without fear of snapping a piece of plastic. And my leg no longer gets tired after 5 songs