From gizmodo.com:

Most people would not describe working out as a pleasurable experience, but nobody said that it has to be complete torture. That’s where these silicone covers for your Wii Fit balance board can help.

The acupressure dots that cover the top of the pad act as a massaging agent for your feet—plus it should provide extra traction when you are dizzy with effort and sliding on your own slippery sweat. The only problem is that I don’t think that Wii Fit is all that it is cracked up to be in the first place.

Source