Sure, there's something to be said for turning a workout into a game, and the Wii Fit has that in spades, but there's also perks to a system that tracks every aspect of your for-realsies workouts at all times. The THP² Personal Training System from Korea's Nury Tec combines a GPS pod, body fat scale and chest strap hear rate receiver to track your well being during and after a workout. All the gadgets transmit wirelessly to a watch controller, which in turn transmits to a PC receiver to download all your stats to an included program. It's like Nike+ on steroids (minus the steroids... don't do drugs kids!), and with a projected price of $180 when this hits the States this year, not a bad alternative on price either.
http://www.engadget.com/2008/05/14/nury-tecs-thp2-training-system-makes-the-wii-fit-seem-a-bit-chi/