So you'd like to do more volunteering but can't find the time? Here's an easy way to do it: Donate the spare processing power on your computer via one of the dozens of ongoing volunteer computing projects, many based on open source software called BOINC. You know, like SETI@home, the well-documented project that uses otherwise idle computing cycles to help "search for extraterrestrial intelligence".
Here's a look at 12 cool projects, with thanks to volunteer computing enthusiast Jonathan Brier and UC Berkeley's David Anderson for their insights. The Web sites for the various projects typically include stats on how much processing power they're using, who is volunteering their processors, etc.