www.romhacking.org
all about ROM hacking. lots of tools and documents. but sadly, no longer hosting sites...

Confederated Translation Company
way-cool group of game translators/hackers

Magick Ink.
lotsa stuff about comics n' cartoons, also home of "Magick Ink. ROM Hacks"

more cool hacks than you can shake a carrot at

Acmlm's ROM Hack Domain
is it just me, or is it strange in here? (home of the excellent "SMB2 Discombobulator!")

Zophar's Domain
emulation news, emulators, utilities, ROM hacks, links, etc.

The Pit of Shite
ROM hacks n' stuff

The Sardius Experience
rarer-than-rare ROMs, game manuals, an undumped games list, a message board, and one cool mofo named Sardius

TheRedEye
ultra-rare, freshly-dumped ROMs, each with its very own detailed review section. a must-see!