Google Glass hack for Apple fanboys can be had right now
Monocular head mounted display. I've got my beady eye on you...
In 2009 I posted an Instructable on how to make a pair of glasses with a head up display to one eye, using a pair of Olympus Eye-Trek video glasses - http://www.instructables.com/id/Glasses-mounted-video-display-to-one-eye-turn-yo/
Since then there has been a lot of interest recently due to the current Google Glass project, which puts a head up display in front of one eye in a very neat package resembling a pair of glasses with nose-piece, top frame across over eyes, but no lenses or lens-frames. Funnily enough monocular displays are much more expensive than binocular ones despite only having the one display as they are perceived as semi-professional devices. The military use rugged versions and also there is a big push to bring them into medical applications.
