Found an interesting open source emulation project called Open Emu for the Macintosh.  modular in design, it currently has support for NES/Famicon, Gameboy/Gameboy Colour, Sega Master System, Game Gear, SG – 1000 and Gameboy Advance.  You of course have to track down the romsets yourself.  Even more interesting, there is a side project named Open Emu QC which will enable Mac VJ users to operate this emulator inside Vj applications like VDMX!  Vade (one of the developers) has some videos here. Get your 8-bit wookie on!