Data from Activity Trackers (jawbone/fitbit/fuelband)?

Has anyone tried hooking up a personal activity tracker (fancy pedometer) to GH?

I'm really curious to know if anyone's managed to establish a live link using one of these devices to drive geometry in Grasshopper, or, if not, at least found a way to use the device's API to link data to GH after the fact. 

I think there is some great potential in this - graphing, for one, to help make sense of the personal fitness tracking data these devices can provide - and of course, great potential for generative art based on personal data.

Has anyone tried this before? Any ideas on which of these devices is the most 'hackable'?

http://www.nike.com/us/en_us/c/nikeplus-fuelband

http://dev.fitbit.com/

https://jawbone.com/up