Folding@Home is a distributed computing project. The main web site for it is folding.stanford.edu
Are you familar with things like Genome@Home or SETI@Home? If so, then Folding@Home is the same type of thing.
The Folding@Home servers at Stanford University parcel out work units to thousands of F@H participants around the world. These many computer systems then process the work units (usually over many hours) and return the results to Stanford. The "processing" consists of running simulations of protein folding. The "work units" are chunks of data from the results of experiments conducted in labs at Stanford. What a protein manages to do in microseconds requires hours of processing time on a computer and the only practical way to process all of that data is to distribute it to thousands of volunteers PCs around the world.
The possible rewards from this entire project are advancement in understanding of many diseases like Alzheimers, cystic fibrosis, emphysema, "mad cow" disease, and cancer. Maybe we can advance the understanding of these diseases to the point of a prevention or cure.
To make things interesting, Stanford assigns a "score" to each completed work unit and posts these scores on their stats page at the site mentioned above. Volunteers can join "teams" if they want, and contribute their score toward their team's total. SPCR has a F@H team, and several of the members here contribute toward the team score.
Once you get into the "competitive" aspect of trying to run up your score and your team's score, you start using the Extreme Overclocking F@H stats site
to keep track of who you're chasing and who is creeping up on you in the standings. The SPCR team is currently #28 in the team standings, but we'll get overrun by another team that's putting up scores faster than us soon. A month or so after that, we should pass another team, so we'll be back to #28 again, and climbing. We were at #30 when I started folding a few weeks ago (not that my ~3000 points contributed since then is the main factor in our move up, but a little bit from many people adds up to a LOT!)
If you're into competition and bragging rights, then the scores and teams will probably lead to an obsession with folding and running up your score. I'm not in much of a position to brag right now. I've moved up 7 spots in the last 24 hours, but 6 of the people I passed aren't actively contributing to the folding effort any more, so I've really only passed one active folder. But now I have DryFire in my sights, and we've been a close match in terms of score production. He's firing up a new machine soon, so I may not catch him, but right now the stats say that I'll pass him and Mr_Smartepants within the next 36 hours or so. Then I'll have to try to maintain my position ahead of them, I'm not sure what Mr_Smartepants is running, but DryFire is definitely not going to let me slack off if I manage to pass him.
See all the fun we're having? It's like being able to race go-karts and have it feed the starving!
Check out the Stanford site above for more info about Folding@Home.
Hope this helps,