It would be fun to be able to have a way to participate in online challenges or contests. For example, interested parties could hold a 5k competition. Participates would enter online, then go do the run, and when done enter your workout (It would be slick if you could make the standard workout log also automatically post to the competition).
Standard races might be boring, so being creative in a way that is similar to velodrome racing might be fun. For example, one could create a win-and-out, which might entail a 5-day consecutive series of 5k workouts. The person with the fastest time on the first day would be the winner and would be done. The person who is the winner on the second day would be second place and so on. These types of races are more strategic then they first appear, because of the consecutive days of running. For example, someone who thinks they can win might run really hard on the first day, but only get the second fastest time, so that person did not win. In fact, that person needs to run another day. On day two, the run finds that he is too cooked from yesterday and can't perform. By the time day four comes around he is the fastest, but he may have placed second if he had raced smarter on day one. Each racer has to choose a strategy and it isn't necessarily to win on day one, which makes the race very interesting. I bet there is a lot of creativity out there that could think of WAY better ideas then these. Of course, the data input would be on the honor system. The reason for this is to get people involved and keep them motivated.