A review of the Fitbit tracking device - WSJ.com

Everyone knows they ought to be eating well, exercising and getting enough sleep. But when they take the elevator up one flight of stairs, drive six blocks instead of walking and skimp on sleep to watch the end of the big game, it's their little secret. Not for long.

I've been testing Fitbit, a tiny $99 device with a motion-detecting sensor that, when worn, digitally records one's distance (walking or running), calories burned and steps taken—as well as sleep patterns. The Fitbit wirelessly sends the data to its Web site, fitbit.com, for storing these minute-by-minute details. And the site has space where users add details like food and water consumption so it provides a more accurate picture of calories burned versus calories consumed...