Green Wii Peripherals??

I love the Wii and its wireless peripherals, but I hate having to make sure I have a constant supply of charged batteries. However a story over Engadget about a power-generating dance floor, got me thinking. Couldn't they create a power-generating wii board? Or a shake generated remote?

I appreciate that one person stepping on and off a Wii board wouldn't provide much power, but how much power does a Wii Fit board need? Whilst the Green Wii Remote could be a scaled down affair that doesn't include sound or vibrating. Would these be possible with current technology??