It's like one of those xbox avatars for runner-types. You can buy a wristwatch device called a sportband (about $50, it is also a nice watch in it's own right) which includes a sensor that is strapped to your shoelace, it then records how you run.
The system used to feature a character that you could customize to your likeness, which would then masquerade as a screensaver on your computer. The whole site was redesigned in fall of 2012 with a much less colorful/cartoon look, it's rather drab now.
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Back on topic... I looked through the avatar gallery and while the artwork is very nice it is not something I would use to represent myself