BOINC
To keep my computers from taking over the world in their free time, I have all of them (except the MacBook) running BOINC by Berkeley. The MacBook is not allowed to violate the three laws, or re-interpret them to take over the world, so it is fairly tame. Anyways, the BOINC client allows the operator to donate the computer's idle CPU cycles to projects they deem worthwhile. Very useful to keep the computers from plotting world domination, etc. Here's a list of the projects I participate in:


BOINC Stats Image