While on [H]ardOCP, I came across a project. Clients are sent information, the client's computer processes the information, and it is sent back to a labratory, just like Seti@home! This might help in finding cures for various diseases. I'm leaving this running for a week on this computer, and it will run while I sleep on my own PC.
http://www.hardfolding.com/index.php?go=93% done after a few minutes, its a slow process. Thats why they could use our help to speed up researcher's work.
I use the no-nonsense console, but you can use the screensaver if you like.