I bought a Playstation 3 a few weeks ago and tried to let it crunch some numbers at Folding@Home. It is amazingly fast! If you still haven't thought about it, you should try to donate some time from the playstation to help science find new medicines.
If you are thinking about how this could waste power and such, fear not if you live in a cold country like me. The first law of thermodynamics states that every single joule of power will eventually heat up your apartment. It's only waste during summer