The Withings WiFi bathroom scale may seem like a strange gadget and a far fetched use for WiFi but it makes sense. Withings offers its users a nice web interface for tracking measurements over time using fancy graphs - it measures weight and fat mass based on electrodes in the glass surface. As long as all users of the same scale have somewhat distinct characteristics, the scale automatically identifies its user.
...and there is also an iPhone application for accessing your data, complete with push notification.
And if family members have similar data, you can indicate which you are by changing your weight on one foot or the other just like operating the Wii Balance Board. Cool.
I got a Wii for Christmas and just invested in Wii fit. Wii fit is more of a toy than a fitness routine. Wasted money and not at all what I was looking for. Actually what I think I really want is these scales and a gym membership. The web interface sounds great.