Although I didn't get round to bringing this idea to life, I still think it's a great one! Let me know what you think. Below is the pitch and a link to a demo app:
Are you bored of running the same routes over and over again? Ever wanted to run in a new place but been unsure of where to go? With runRoute you simply need to type in a distance. You'll get a different route each time and at the end you'll be back where you started!