Dozens of fitness-tracking apps for smartphones – like RunKeeper, MapMyRun, and Fitocracy – are great choices for connecting to social networks but don't do much else besides track your run. Runtastic's Pumpit app suite counts squats, pull-ups, and sit-ups with its accelerometer, as well as push-ups with the phone's proximity sensor. Every time your nose nears the phone, the app gives a satisfying ding, pits you against the current record, and adds it to the community's 83,906,930 push-ups – and counting.