I'm only supporting the SETI program because I'd love to hear one day that we're not alone out there (or else it would be an aweful waste of space :p).
As a hobby programmer, I have my system up for around 10 hours a day and hardly using the CPU/GPU power my PC offers. Having a 6-core system, SETI@home can just run in the background unnoticed while I'm bugging around with code ;-)
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.