BMW have developed a concept for AR glasses that can assist their own mechanics in performing maintenance on the company's high-performance cars. The glasses read the field of view, point out the part that needs replacing, the screw that needs turning, or the cap that needs tightening (and even tells users which way to turn it).
One of the most common uses for them is on mobile devices. 2d barcodes like QR Code or Datamatrix can activate phone functions - they can create an SMS for you to send, or send your mobile browser to a particular website. The entire URL can be stored in a 2d code thanks to it's greater data storage.
Tagwhat is a consumer-facing product that allows people to tag real-world locations and attach information, reviews, links, photos, videos, notes and so on to those particular spots, whether tied to their current location or not.