I saw someone running inside a parking garage the other day.
They were running for fitness, and the garage was very large and it occurred to me that it would be both easy and cool to paint ‘trails’ on the floor of the garage, post the distances for the trails, and then you could have a known distance running circuit. A simple web app could have the trails and catalog your times, a kiosk at the starting place could even manage the stop watch for you, and the whole thing would be a pretty damn cheap way to get in some miles at work, particularly in inclement weather.