Master System, GameGear, SG-1000, ColecoVision and Nintendo - FreezeSMS
PlayStation - ePSXe and pSX
Genesis, CD, 32X - Gens (but most of my Sega CD games don't run
)
Saturn - SSF
Dreamcast - nullDC
Nintendo 64 - Project 64
GameCube - Dolphin
PlayStation 2 - PCSX2