The video below shows a little demo I wrote as a proof of concept for the use of the Leap Motion controller as a tool for Augmented Reality applications.
What you see is a simple virtual world (just a blank room). As the user reaches in front of their face, where the Leap is attached, the hands are detected. At this point, two viewports are created at the position of the user's hands. These viewports are fed images directly from the Leap's twin infra-red cameras. If one were to affix the Leap to the front of a Head Mounted display, such a set-up could be used to allow the wearer to "see through" the device.