As if the Wii weren't enough of a workout, you could strap on the Wii Weights to your wrists and shed more pounds than this guy. Inserts allow for three levels of activity from featherweight (1 lbs.) to heavyweight (4 lbs.). Plus an eyelet helps keep your controls away from the plasma tv.
Unfortunately, this is only a prototype looking for an investor to take it to market.
Send me an email and I can hook you up with the "inventor".
UPDATE: Wii Weights: Part Two