http://ipmart-forum.com
THE site for the BEST hacked, cracked, and key genned software and games for smartphones, ppc, palm, and 'puters.
http://www.xda-developers.com
EXCLUSIVELY for HTC devices. Custom roms, great community atmosphere, and some great developer software and resources.
http://www.ppcgeeks.com
Another EXCELLANT site for winmo pocket pc's.