You can use your spare CPU cycles for worthy projects, such as cancer research.
What happens is you download a small program that will process information (usually about molecules) and upload the results. This is all automatic and in the background. You won’t even know it’s there. This may help to eventually cure some diseases.
User’s results are tracked and displayed individually, but you can also join a team or form a team or your own. Someone could create “The Straight Dope” team!
Currently, I’m working with http://www.find-a-drug.org/. The people in their forum are very friendly and helpful.
Here is a good list of distributed computing projects:
http://www.aspenleaf.com/distributed/distrib-projects.html
I like thinking that my computer is always doing something useful. Why not sign on for a project now? It costs nothing and is pretty neat.