• Game Boy / Color / Game Boy Advance
• Nintendo Entertainment System [ NES ]
• Super Nintendo Entertainment System [ SNES ]
• Nintendo 64
• playstation psx link to another post on this site
• OpenEmu

If you are looking for a standalone gameboy / gameboy advance emulator, then try KiGB

• get KiGB
• with the emulator enhancers
• drag the app to your applications folder.
• copy the emulator enhancers folder to ~/Library/Application Support/
• run it with some roms.

or you could try Virtualboy advance

Openemu supports SNES, but if you are looking for a standalone emulator then try Snes9x [or znsnes, or bsnes]

Snes 9x is an awesome emulator for snes games.
If you run the standalone snes9x rather than the open emu component then you can follow this post and use your iPhone as a snes controller :)

combined with an AppleTV and the new multiple desktops features on osx mavericks you can [nearly] play the games as well as it were an actual snes!

http://sixtyforce.com

open emu supports:

• gameboy / colour / advance
• nes
• snes
• sega mastersystem
• sega gamegear
• sega genesis / sega megadrive

when you first install open emu it will ask if you want to install ‘cores’ these cores are actually full emulators
I just clicked ‘install all cores’.
In the beta version the game browser isn’t available, but you can still load roms by going to the file menu.
I was able to play snes games, and I was able to play gameboy advance games (zelda) with no problems.