EatMyDirt!, the iOS application that allows you to run against real people in tracks near you.
It's simple: you have a map with checkpoints and you go through them to finish the race.
Tracks are created for a specific transport, and rated by other runners.
Create your own tracks, challenge your friends or try to beat records in nearby tracks.
Get points for being among the fastest or by having people run your tracks.
Try it out and have fun!