Aural augmented reality
Sophisticated augmented reality is technologies already exist for audio. Digital hearing aids can be configured to include or exclude different kinds orof sounds, like refrigerator and fan noise, and different modes of hearing can be chosen. Cell phones can be used in conjunction with hearing aids (and inductive loopsets), allowing people to talk on a cell phone while blocking all background noises sounds lololololol (Bluetooth in hearing aids means they don't need to wear headphones or use a headset).  This can be combined with subvocal speech  to essentially make practical telepathy possible.
Augmented reality in tourism
Tourist augmented reality systems are being developed. The last one recently publicised (a pilot project in UK) had GPS, hotspots in the tourist area, a handheld computer (tablet?) and it could deliver custom multimedia location-specific content. You stand in the yard of the castle and you get one story, go to the gate, get another story, come to the embrasure, see/hear a third one.
Another project is older (can't remember the link now - here is a more traditional one), it was tested in Greece and was intended to provide VR overlay over ruins, so that you can see how the building looked using VR glasses, see the people of the past, etc.
Also interesting is that we are bound to see a lot of "unauthorised" and/or user generated content (illustration/analogy).
Glasses for kids to transform their house into a castle. E.g. a kid is living in a trailer, but the glasses change it into a king's castle or a magical forest, etc. Rose-coloured, or even pink-coloured (Hello Kitty-branded) modes can be available. Animated books that use augmented reality have already been demonstrated .
Currently handhelds are used a lot in many AR projects. (example) Eventually glasses will be used more and eventually implants.
Right now AR usually involves 3D models placed on markers or sometimes information overlays. Eventually it will be dynamically incorporated into real world without markers (feature extraction has already been demonstrated - google for "agumented reality kitchen"). And more modifications of real world objects will happen (like with Toshiba demo  here).
- the first version of this article was a comment to this blog post
- Futures Wiki
- Videos from Total Immersion, one of the leading companies in the field.
- real-time structure from motion -- be sure to see the Kitchen video
- WearCam.org - lots of information
- Future Augmented Reality - how tech and people will benefit from this innovation.