The SuperNES has a few emulators. SNES 9X is the best. There is a carbon version for both OSX and Classic OS

Snes 9x Homepage
Virtual Super Wild Card Hompage

The NES has Nestopia and RockNES. While NESTopia is strictly OSX, rocknes has a Classic Mac version as well 
NEStopia
RockNes

Nintendo 64 Emulators are getting more compatible every month, but there are still some games which do not play well. Sixtyforce is the best.
SixtyForce.

nestopia


Even the I-phone now has a nes emulator!

smb

A nes emulator! No sounds yet, and I wonder how a touchscreen plays but it just looks lovely
Homepage