MEKA  
   A freeware emulator for DOS, Linux/i386, and Windows. Supports ColecoVision, Game Gear, Master System, Othello Multivision, SC-3000, Sega Mark III, and SG-1000.
   http://www.smspower.org/meka/

Mimic  
   Freeware emulator for DOS. Supports Game Gear, Gameboy, Master System, Mega Drive / Genesis, Sega System E, and some Arcade games.
   http://mimic.arcadeheaven.com/

DarcNES  
   An open source emulator for AmigaOS, BeOS, BSD, DOS, Linux and Windows. Supports the Apple 2, ColecoVision, Game Gear, Master System, MSX, NES, PCE/TGX, SC-3000, and SG-1000.
   http://www.dridus.com/~nyef/darcnes/

FreezeSMS  
   A freeware emulator for Windows. Support ColecoVision, Game Gear, Master System, NES and SG-1000.
   http://freezesms.emuunlim.com/

Emulator 3000  
   A freeware emulator for Windows. Supports various russian and foreign computers including Agat-9, Bashkiria-2M, Elektronika BK-0010*, Mikrosha, Partner 01.01, Pyldin-601*, Vector-06C, and ZX Spectrum.
   http://www.emulator3000.emuita.it/e3.htm

Xe  
   A freeware module based emulator for Linux/i386 requiring GTK+2.0. Supports Game Boy, Game Gear, Master System, Mega Drive / Genesis, Neo Geo, Neo Geo Pocket, NES, SG-1000, Super NES, Turbo Grafx16, Turbo Grafx CD, and WonderSwan. Incomplete Mega CD and N
   http://www.xe-emulator.com/