As a rabid football fan (go JETS!), I am more than a little excited by the Replay Football app. The Replay Football app is an Android app developed by Ben Kokes that tracks the crispness of your passes using "a Bluetooth-enabled Nerf football with a 9-axis inertial sensing motion processing module (MPU-6000 by InvenSense)."
In layman's terms, the Replay Football app tracks the crispness of your passes, analyzing both the good and the bad. Currently, the app is only used for analysis, but here's hoping that Kokes refines it and attempts to bring this bad boy to the mass market. I think everyone from weekend warriors to professional football players could benefit from having an easy-to-use and pocket-sized analysis tool readily available.