Megasis
Freeware emulator for Windows.

Virtual Genesis
Freeware emulator for DOS.

Consoles - Megadrive
A table of the latest emulators and their ratings.

DGen/SDL
Open source emulator port to Unix/SDL.

Generator
Open source emulator for AmigaOS, DOS, Linux, MacOS and Win32.

Gens
An open source emulator for BeOS, Linux, and Windows. Multilanguage and Sega CD support.

Xega
Freeware emulator for Windows. Supports 32X and Sega CD.

Genecyst
Freeware emulator for DOS.

Gametown
Offers a few ROMs.

Blades Of Vengeance
Some ROM Images.

DGen
Open source emulator port for MacOS.

FreeRoms: Genesis
Alphabetic sorted ROM list with rating system. (607+ ROMs)

retroDrive
Freeware emulator for Windows. Supports 32X. Previously known as Gensx and Vegas.

PGEN
An open source emulator for PlayStation2 based on Generator.

AGES
A freeware emulator for Windows. Supports 32X and Sega CD.

Sega Roms
Small ROM site with reviews. [English/Turkish]

DCGen
A Dreamcast port of Generator.

Genital
A freeware emulator for DOS.

Genesis Plus
An open source emulator for DOS, MacOS, and Windows by Charles MacDonald and Richard Bannister.