Motorola's MOTOACTV may be the most versatile wearable fitness device on the market today — though that doesn't mean it's the best for everyone. The MOTOACTV can track just about any kind of workout, includes a media player, and it's rugged enough to handle sports like mountain-biking. It can also be upgraded with new functionality simply by downloading new apps. The downside? It's heavy, and its web site has some bugs and isn't user-friendly as those of competitors. If all you need to do is track steps, calories burned, and other basic workout stats, you may find a less expensive option like the gdgt Must-have Fitbit Ultra to be more appropriate. But if you want a full-featured, upgradeable, wearable (albeit heavy), fitness tracker, MOTOACTV gets the job done.