The Fitbit's sensor was developed to track 3D motion throughout the day, with a sensor worn clipped onto clothing, in a pocket or attached to a wristband. The unit is capable of monitoring how well you sleep by tracking movement; the less you move, the more likely you've been enjoy deep sleep. And since sleep is a significant aspect of good health and optimal training, the feedback can be helpful to make lifestyle changes (no big steaks or drinks right before bed time).
As former users of the Nike+ system, we've had good experiences using similar technology in aiding our fitness goals, as data feedback can be an addictive and helpful tool for meeting specific health goals. What we like most previewed is Fitbit's user friendly and informative user website. Tabs for "Food", "Activities", and "Weight" are clearly labeled, with the option to keep close records of food consumer, hydration, and activity vs. intake. Everything is presented in a user friendly site that makes it similar to a Web 2.0+Facebook experience. A Windows and OS X compatible base station uploads all your info when you dock you Fitbit unit at the end of the day and it appears a social networking system features prominently as part of the Fitbit experience (motivation and support from others is often a great aid in long term health goals). We can't vouch for how effective the unit is yet, but we're hoping to nab one for testing in the near future. We dread discovering how inactive we are day to day sitting behind a keyboard, but perhaps that's the reason to get one in the first place. The Fitbit is now available for $99.