My main running app is MapMyRun by MapMyFitness. There are many other similar apps for runners, but for some reason I have gravitated towards using this one when I run outside. I also exercise with my Polar GPS watch and heart rate monitor to quantify my running pace with my overall cardiovascular fitness.
Several days ago, Under Armour announced that it would be acquiring MapMyFitness for $150 Million. Even though Under Armour has their Armour39 fitness tracker, this device isn't designed for the average fitness enthusiast. I'm sure that Under Armour will be releasing a wrist-worn activity tracker to directly compete against the Nike+ FuelBand.
Everyone is getting serious about fitness and activity tracking. Wearable devices. Quantified self. It's all coming together and as major athletic manufacturers invest in trackers and apps, we'll soon find ourselves exercising in a more data-driven, data-centric model.