Emulators
Nintendo
Genesis
Master System
Super Nintendo
Arcade

Roms
Nintendo
Genesis
Master System
Super Nintendo
Arcade

FAQs
Emulation
Super Nintendo
Callus

Links
Rom Sites
Emulation News
Random

Zophar's Domain
Great emulation news site updated daily.  Also check out their SPC player, ZDSPC.

Dave's Videogame Classics
This is an awesome emu news site!  Very well put together, and I get most of my emunews from them directly!