Nintendo have sent
us some information about Club Nintendo, a new scheme that allows you to swap Star points which you can redeem for exclusive Nintendo swag:
Mario Kart Wii, Wii Fit™ and future participating products will come with a unique PIN code which allows you to register that you have purchased a particular game, and that’s when Nintendo rewards you. Simply visit www.club-nintendo.com to input your unique code and join Club Nintendo where you will receive Star points credited to your membership account. Use your Star points to redeem Nintendo goodies from the Stars catalogue, which is only available to Club Nintendo members.
The referred-to Stars catalogue is not available yet so not really any indication as to what you can get, but (assuming you have a supported title like Mario Kart), you can register your Star points now.