If you have not heard of it the search for extraterrestrial intelligence, or SETI, has been listening for decades now for a hint of a radio broadcast from outside our solar system, They have an array of antennas listening almost constantly. The approach known as radio SETI, it uses radio telescopes to listen for narrow-bandwidth radio signals from space. Such signals are not known to occur naturally, so a detection would provide evidence of extraterrestrial technology. Being privately funded they could not afford a super computer to crunch through all of the data they would gather so they turned to the public. In 1995, David Gedye proposed doing radio SETI using a virtual supercomputer composed of large numbers of Internet-connected computers, and he organized the SETI@home project to explore this idea. SETI@home was originally launched in May 1999.
This search uses your unused personal computer cycles, along with cycles from all of the other participants to in effect form a super computer. This requires you install a small client on your computer. It will fetch observation data from SETI and then process it on your computer and send the results back to SETI. The client is configurable so it can run without impacting the use of your computer in any way. In addition you get a really cool screen saver which displays the data as it is analyzing it.
If your lucky enough to be the person who detects the first signal from alien intelligence you will be named as the co-discoverer and your name will go down in history for this momentous achievement. The software is free, you get a nifty screen saver, your can sleep better knowing that your un-used computer cycles are being tasked with something productive and not just wasting electricity. What more could you ask for!
You can get the software and join SETI here. The have software for all flavors of computer, Linux, Windows, Mac etc. Join thousands of others in he search, SETI WANTS YOU!