After a year of waiting, the FitBit will be officially in the market by this month. The FitBit is a gadget you can flip on to your shirt which will in turn determine how much exercise you have been doing and how much calories you are burning. The device can also track your sleep patterns based on movement. In this case, you can convert it to a wristband since there are some people who may not necessarily be dressed to sleep.
The FitBit will retail for $90.
(Source) Gadget Review