The Dolphin Emulator has been posted on HN before it emulates both the GameCube and the Wii. That is the one emulator that impresses me the most... You can play online with other Wii players if you extract some info from your regular Wii, aka make your Wii immortal to a degree by digitizing it...
There is a Wii U emulator kicking around. And a few 3DS emulators -- which is a hoot, given that the 3DS is still a living, supported system getting new retail game releases weekly.