Despite my skepticism about head-mounted displays, I remain enthusiastic about the possibilities of ‘augmented reality’ – it is just too cool for words!  Here you see a research project that lets folks run around a (real not virtual) college campus, and shoot at monsters from the game ‘Quake’ that are superimposed on their vision.  The game knows about the real geometry of the campus, so it can present or hide the monsters appropriately.

There are so many interesting directions this technology could go – games, information about real-world objects and events, even replacing a real object with a different representation of it.  In theory, for example, you could make everyone you meet look like a dinosaur.  (Not sure why you’d want to, but hey – different strokes for different folks!)