Slightly obsessed with tracking your workouts? Grab your iPhone and discover the wonderful world of free (or dirt cheap) running apps. The built-in GPS allows you to track your run no matter where you are: on trails, busy neighborhoods, or dirt roads. Whether you want an actual Google Map of your route, a calendar showing off the days you worked out, or to share your workouts with your pals on Facebook or Twitter — there's an app for that.
Don't Assume Your Mileage: iPhone Apps For Runners