Ace Combat-The old controls are dead in the water. This series needs to be on the Wii, and I think the balance board can handle the flight manuevers. Weapons would still be controlled by buttons on the Wiimote.
Katamari/Mercury Meltdown/Super Monkey Ball/Koroinpa series-Just roll your feet around to make the ball move in different directions. To jump, just stomp the board.
Pinball-Have the left side be the left flipper and the right side be the right flipper. Stomp to tilt the table.
Zelda on horseback-Use the board to control the horse while freeing up the remote for the bow and sword.
Tetris-Stomp to flip the piece and slide side to side or down to move and increase speed downwards.
Wii Music(drums)-Use the remote and nunchuck for drumsticks and the balance board as the pedal.
Racing-The pedals...obviously.
I'll think up more later. I believe there's a lot of potential in this board. Not eveything I mentioned would be the ideal way to play each of those games, but as one of a few control options, it might seem fresh to play that way. If I can think up this, and others can think up theirs in minutes, imagine what the right developer can do with it.