If you are a fan of distributed computing projects such as Folding@Home, you've likely heard the rumors regarding a client being released for the PlayStation 3. Soon, it will be released, with Sony already have demonstrated it last year. The client, which will run when your PS3 is idle, works much in the same way the PC client does and can be configured to report results to a Folding@Home team. What's most interesting is that supposedly the client for the PS3 will be able to complete a single work unit 10 to 30 times faster than a desktop PC - that's beyond impressive, if true, and shows that the Cell processor does have a lot of potential with software optimized for it. Then again, this is a claim coming straight from Sony, who have more than enough incentive to play up the PS3.
It's an interesting project, and if you have a habit of leaving your PS3 on all the time anyways, you might want to give it a try.