Best video game emulators for OS X

i wonder the same thing though ..

Snes!

go to http://www.snes9x.com
there are links to mirrors with a few builds, Mac OSX included!
works great in 10.4 (not tested in 10.5 personaly yet)

These are the best OS X emulators in my experience...

Nestopia (NES)- http://www.bannister.org/software/nestopia.htm
Snes9X (SNES)- http://www.versiontracker.com/dyn/moreinfo/macosx/21188
KiGB (GBC)- http://www.bannister.org/software/kigb.htm
VisualBoyAdvance 1.7 (GBA)- http://vba.ngemu.com/downloads.shtml
PSX is unsupported, as far as I know..
You can find more here: http://www.bannister.org/software/emu.htm

All of these work GREAT and are compatible with Leopard.

SixtyForce is a decent N64 emulator.

http://www.sixtyforce.com/