RomCenter Home Page
Managing tool for various systems with built-in zip function.

Emulationnation
Small ROM Site. Provides 36 C64, 5 ZX Spectrum, 7 Genesis, 14 Mame, 1 System16

The Dump
Rated, working ROMs for Neo Geo, Genesis and TurboGrafx-16.

ClassicGaming.com
Large collection of ROM Images, and emulators for classic systems.

Demo Roms
A nice collection of Technical Demos (some with source code) for various systems. Sadly not anymore updated.

Dave's Emu
Public Domain ROM Images for some systems.

buttonBASH!
Public domain ROM Images for various systems. Also features a forum and some tools and documents.