I use SETI (and especially it's BOINC software) because the idea of using left-over computing power from zillions of idle, personal computers to solve such massive math problems is waaaay cool.
SETI@home and Astropulse are funded by grants from the National Science Foundation, NASA, and donations from SETI@home volunteers. AstroPulse is funded in part by the NSF through grant AST-0307956.
