The Fitbit Flex ($100) is a slim, minimalistic wristband. It tracks your activity level, sleep quality, calories burned, and distance traveled; you can program the lights on the band to indicate real-time progress on hitting your goals. The Flex also vibrates to wake you up and wirelessly syncs to automatically update your stats whenever it's in close range of the included Bluetooth-enabled wireless dongle, which plugs into your computer's USB port; you can also wirelessly sync to your iPhone, iPad 3, iPad Mini, or Samsung Galaxy. If you like the features of the Fitbit Flex but don't want to wear a wristband, then try the Fitbit One or Zip.
Another FitBit Flex sibling, the FitBit Force (currently unavailable), is a similar-looking tracker. However, in 2014 the Force was recalled due to an allergic reaction some users experienced when wearing the band. Like the Fitbit Flex, the Force tracks steps, calories, and distance as well as sleep stats; unlike the Flex, the Force also can gauge how many stairs you've climbed and elevation, and it features a display, as well. The water-resistant Force syncs wirelessly and automatically to your iOS or Android phone or computer, so you can view your stats on an app or browser. Since the current Force has been recalled, keep an eye out for the next-generation model of the band soon.
I have one and I love it. It truly motivates me to do my daily exercises