These are emulators which allow you to play games.
GameBoy Emulators
no$gmb(the best emulator for Gameboy I've seen)
Nintendo64 Emulators
UltraHLE(The best 64 emulator)
X-Glide(You need to download this to run UltraHLE)
Super Nintendo Emulators
ZSNES(the best one out there for SNES)