ROM Hacking Links

romhacking.net
General ROM hacking community site that aims to bring several different areas of the ROM hacking community together. It has a large database of patches, utilities, documents and fonts.

Zophar's Domain
Once was one of the central place of ROM hacking but the activity there has declined gradually.

Insane Difficulty
Forum dedicated to difficulty hack on many systems. RotDS and Brave New world have a subforum there as well as other mods.