The first scale that connects wirelessly to the Internet, Withings uploads your weight and body-fat percentage to Web sites like RunKeeper.com or Google Health for tracking, or even to an iPhone. You can measure only weight, body-fat percentage, and body-mass index—but it's pretty much idiotproof. $159; withings.com
Tanita BC-1000 Scale
The Tanita BC-1000 is one of the best scales for fitness fanatics.
Instead of a screen, the BC-1000 sends your numbers to a Garmin FR60 heart-rate watch ($80) or a $130 remote display and can sync to a PC via a USB drive or an iPhone. While the user interface can be tricky to master (old-school Windows software and no Mac compatibility), the Tanita offers ultra-serious athletes enough data to crash a supercomputer. $280; tanita.com