RunKeeper

Available for iPhone and Android, the RunKeeper App allows you to track your physical activities and see how you're progressing (running, walking, cycling, etc.)

Considering lots of people give up on their routines because they feel like it's doing nothing, having a reliable measurement system that lets you know if you're doing better or worse than your last workout can be all it takes to keep you motivated and wanting to do better and better.

(And I have to admit, it's really satisfying to receive RunKeeper's emails congratulating you for having run your farthest distance.)

The RunKeeper service is free, but some options are only available to the paid "elite" members.

The App uses the GPS to store your routes - which can be kept private, or shared with just your team, or made public - and while you're running, it will give you voice feedback about the distance, time, and speed. That alone let's you know how you're doing... while you're "doing it".

If you're a RunKeeper user, you can find me here.