The first third-party add-on has been shown, a steering wheel from Ubisoft which clips around the Wii-mote!

Developed by Thrustmaster and to be released by Ubisoft along with its upcoming GT Pro game for the Wii, this new attachment has a hole for the Wii-mote to clip in the middle, allowing a realistic steering wheel-style grip to be had while turning corners and burning rubber in the game.

Usable on practically any racing game (or any Wii game, to be fair), this new accessory should add a realistic touch to the driving controls. A high-res picture can be found on IGN here!