The FLIR ONE personal thermal imager is an infrared camera that snaps on to the back of your iPhone 5, allowing you to shoot infrared videos and stills. I’ve played with one and they are fun, easy to use and work well.
The down side of the FLIR ONE is that it can be used to pick up pin codes and other lock combinations by tracking the heat signature left by your fingers. The video embedded below shows how this is done and how to prevent it. Worth a watch.