Augmented reality: We see what you see.
The idea behind augmented reality is, you point a camera-enabled device at something and instantly get information about it. With Autonomy Aurasma, for example, you could point a device at a still photo from a sporting event. The device could identify the scene and start playing a video clip. Google, meanwhile, will reportedly release Google Glasses through which you could, for example, look down a city street and see digital details overlaid of the screen (e.g. street names, areas of interest, or directions).
Augmented reality has cool applications for entertainment, education, and business. But with it you're pretty much letting a third party "see" in real time where you are, what you're doing, who you're with, etc.