Fitness freaks and health nuts, record how much exercise you're getting at rest and during the day with the Fitbit Tracker ($100). This wireless, clip-on device uses internal sensors to monitor your movement and activity level. The Fitbit keeps tab on the calories you burn, the steps your take, the miles you walk, the sleep you get and more. This Tracker syncs wirelessly with its base station, allowing you to upload data online, where you can track your fitness goals and collaborate with family and friends.