Nintendo has just announced a Gamecube controller adapter for the Wii U. No really, we are not making this up.
Smash Bros fans will rejoice as using the Gamecube controller is arguable one of the best control schemes around.
Details are scarce but it will support up to four GC controllers. Pricing has not yet been announced but hopefully Wavebirds will also be compatible. It also seems that both front USB ports on the Wii U must be used to power this device. No word yet on how long those USB cords are either.
You can also try shopping at a local 5Below for cheap Gamecube Controllers as well (sorry for the broken image links).