UPDATE 15th March 2013: I have newer better version of this now in another Instructable:
Believe it or not the real purpose of this project was not to play at being a Borg.
I needed to make some form of wearable head up display that also allowed me to work simultaneously, i.e. see what I was doing at the same time, to test the feasibility of a concept for a research idea I have had. I needed to for example be able to remotely watch a video screen with data on it and also later may want to view protocols, checklists etc on this "head up" display.
My interest in this is because I think wearable displays will be a valuable tool in hospital medicine, especially in anesthesiology.
The proper name for this is a monocular HMD (Head Mounted Display).
A number of video-glasses already exist for watching DVD's for example and these generate an image for each eye. The downside is that you cannot see your surroundings while wearing them.
So-called monocular (one eye) displays do exist but can be very expensive. I already had an old pair of Olympus Eye-Trek(TM) video glasses, which are (relatively) inexpensive and decided to hack them and embed one of the display units into a pair of workmans safety glasses.
Then, having made this display work, I used the innards of a wireless security camera / receiver combination to make the system work wirelessly and finally packaged all the circuits with appropriate batteries into a just-about-pocket-sized container.
This project might also interest the "wearable computer" fraternity. You could also attach an infra red camera to it to give yourself night-vison.
Here is another view.
The box on the left contains a video receiver from a low cost security camera video transmitter / receiver combination plus batteries, plus the drive circuitry from the Olympus Eye-Trek(TM) video glasses.
The small circuit board and one set of optics from the video glasses are mounted in the safety glasses on the right.
These glasses may look bulky but it is actually better than some commercial systems out there, very light in weight too.