Fraunhofer IPMS have done what many companies in the past have tried and failed at, creating a Borg-like eye-tracking display. This bidirectional, eye-tracking OLED microdisplay does a lot of cool stuff. The transparent OLED display shows off a bevy of information, usually in the form of an overlay.
The unit also includes integrated photodetectors and special software to monitor the direction of where you are looking. This opens up a host of potential augmented reality applications. The unit is just a concept for now, but the creators see it being used, among other ways, for joggers to watch movies as they jog. Youch. Dangerous.
There’s also the notion you can spy on someone as you, well, spy on someone. This could be done by using the display to Google people you meet as you meet them. Big brother alert. More on this intriguing tech as it develops.