runnr.net is a new kind of super marathon app which brings people together to tackle super-long-distance courses that no one could run alone. Available courses include The Great Wall of China, Circle the Globe, Run to the Moon, Run to Mars, and lots of other courses that one person could never finish. When the total distance run by all participants reaches the end of the course, the next course is unlocked!
The more people participate, the sooner the group can clear the course (probably).
It's free to join in!
Try it now, and get involved in a super ultra marathon like nothing anyone has ever seen!

!--- Continued use of GPS running in the background can dramatically decrease battery life. ---!