Phone Punx Network
United Phreak Pimps
l0pht Heavy Inustries
OTHER STUFF I'M INTO:
ticalc.org -- All about how to program calculators
GameBoy Development Ring -- same as above, but with the Nintendo GameBoy
One Minute Left -- For all your emulation needs
Y2K survival Documents -- I know it's over, but there is some cool stuff there.
Flannel Dog Productions -- Support the hell out of them.