Both HUDs displaying information and augmented reality (overlaying digital info on real-world objects) have tons of practical uses ... i saw several videos with prototypes of these, most famous of course if the Google Glasses, but i saw other interesting stuff like augmented vision for fire-fighting helmets which diplays lots of vital information and has other functions as well.
That's one of the prototypes for the fire-fighting helmets --> http://www.youtube.com/watch?v=yHIynl9W3GM
simply said, HUDs and augmented reality visors have almot limitless potential .. specially if all the supplementary tech is provided.
For example .. in a super market, food packages would have a small microchip that transmits all info about the food package directly into the HUD from distance (in the form of small augmented reality pop-ups) and you can customize which info to prioritize and even choose which food-types/brands to display info and which don't at all so you can find what you want in seconds .. apply that to everything from police work to doctors and you can see how much potential it has.