Well, this is my updated list of the great emulators on the Wii:
Nintendo NES - FCE Ultra RX
Nintendo SNES - Snes9x RX
Nintendo N64 - Not64
Nintendo Gameboy/Gameboy Color/GBA - mGBA
Nintendo Gamecube - Nintendont
Sega Master System/Sega Genesis/Mega Drive - Genesis Plus GX
Neo Geo CD - Neo Geo CD Wii
Neo Geo AES/MVS - Retro Arch with Wiimpathy version of FBalpha
Capcom System 1 CPS 1 - Retro Arch
Capcom System 2 CPS 2 - Retro Arch
Turbo Grapfx - WiiMednafen