Motorola's MOTOACTV is a super-versatile wearable fitness device, with built-in GPS and (with a chest strap) heart rate monitor good for tracking nearly any kind of workout—running, cycling, skiing and even cricket! Beyond that, it's a "smart" mp3 player that holds up to 4,000 songs and, through some feat of electronic wizardry, "learns" what kind of music motivates you and can DJ your workouts accordingly. Beyond that, its functionality can be upgraded by simply downloading apps onto it.
$150 (8GB), $200 (16GB); motorola.com