With all this talk about making life easier by controllong other devices from your phone while you lay in bed, it might be getting a little too comfortable around the house. So it's time to get out. Marathon is a fitness app that records and saves your movements during runs or biking sessions. It'll track your calories burned, speed and altitude changes, and you can let your friends track your running progress live online, if you're so inclined. If you're the type to run by yourself, you can also race against your by trying to best your previous results. You can also publish your results on Facebook and Twitter.