via http://www.aep-emu.de/

BizHawk is a multi-system emulator in C#.

Supported Systems

Nintendo Entertainment System (NES)
Sega Master System
SG-1000
Game Gear
PC-Engine (TurboGrafx-16) / CD-ROM
SuperGrafx
TI-83 Calculator

Experimental

Sega Genesis (low compatibility list)
Gameboy (Debugger only)