Nike Plus Running is an app I recently started to use. What I like about the app is that I can track each run, and learn about my pace, distance and progress. You can link your account to Facebook (which I choose not to do), find friends using the app and find routes pre-mapped by other users. During runs, the app will notify you at certain distances of your distance and pace. You can also link your iTunes to it and listen to playlists during runs.
To make this exploratory video of the app and website, I used Knowmia and Screencast-O-Matic. Enjoy!