It would be great if the Healthmate app would have an ability to record waist (and other body parts) measurements and the progress graphs. Waist measurement is really important indicator of excess weight even more accurately than BMI.
Just ability to enter the information would be enough with a traditional measuring tape could be a good start.
As selling the devices is the business of Withings, one step further could be an electronic measuring device (measuring tape with bluetooth) that could send the measurements to the system via phone same way as the blood pressure meter is working now.
How about this?