7. The Fitbit ($100; www.fitbit.com)

Why we like it: Clip the Fitbit onto your waist—or just place it in your pocket—and this 3D motion sensor can help you track everything from how many calories you’ve burned to how many steps you’ve taken (including how far you’ve walked) all day. But what’s unique about this gadget is that when you wear it at night, it can even gauge how long you’ve slept—along with how many of those hours were actually quality hours of sleep. Better yet, every time you walk past the base station, the Fitbit wirelessly syncs your daily data into your online profile, so you can see how well you’re doing without ever having to type a single thing.