Nike has the Nike + that works in tandem with your iPod or through the Nike gadgets. They work as most GPS units do with tracking distance, pace, heart rate, time, etc. But with the iPod it adds some little features with your music and a nice pleasant voice telling you how far you have gone. Now Adidas has jumped full speed on the party train with their version, the miCoach.
It does most of the same features as the Nike +, but adds the goodness of a coach yelling at you when your workout isnt up to par. I dont know if you can change the voices or if it is in German accent, but I can imagine in some instances having coach Dider yelling at you that your effort is worthless would be inspiring.