Mac users interested in Nes emulation for osx 10.6.8 generally download:
Nestopia is a Nintendo Entertainment System (NES) emulator for the Mac. It allows you to play ROM files, which are dumps of NES games. You are legally allowed to play any ROM files of games that you own. The emulator doesn't require any configuration at all. You can just load a ROM and start playing.
Additional suggestions for Nes emulation for osx 10.6.8 by our robot: