What It Is: Skipping a workout is a lot harder with cold hard cash on the line. GymPact lets users ante up and tie a monetary incentive to working out.
Why It's Cool: Users who check in at their gym with the GymPact app get to keep the money they put up, while those who miss a workout lose a predetermined chunk of change. GymPact also features integration with RunKeeper (one of our top apps!) and at-home workout options.
Cost: Free. Available for iOS and Android.