TrackingPoint
TrackingPoint's Precision Guided Firearms app accurately mirrors the view from a rifle's scope onto a selected mobile device or Google Glass. This provides a head-up display similar to what a fighter pilot experiences in the cockpit. This could allow a shooter to aim and fire from around corners and behind walls, while still taking advantage of extreme cover.
The U.S. Army has recently purchased six TrackingPoint systems for its own testing and use. The military has been pursuing technologies that could enhance soldiers' situational awareness, and some reconnaissance troops are slated to test a military spin-off of Google Glass.
Meanwhile, the Air Force is also testing Google Glass for possible battlefield applications.
Below is a video from TrackingPoint showcasing their ShotView app.