Augmented reality is a virtual layer over the real.world, hence the name. The possibilities are endless since you can feasibly create anything graphically, whether its a 3D sculpture or a 2d layered composition, if you have the file you can import it into Adobes Adobe Aero and place it in the real world, even places you've never been before using their mapping feature.
On a basic level, its very easy to use, AR already has assists you can use just to get a feel for the app and like I said you can import your own models.
Last year for our branding module I created a brand to direct people to get rid of their cigarettes properly, I made this logo of an ashtray with a cig in its mouth, which id branded as a sticker, amongst other things. Back then I had simply photoshopped it around Leeds but with AR I can get an actual look at it.
ARvid
I found this AR app called ARvid which isn't at technologically advanced as Adobe Aero, but it also has models, you can write and has a lot of similar features, but what I liked most was the drawing aspect, even though its not the best, its instant and quick.
Problem with it though is that it layers funny, the brushstrokes can go anywhere so things can go behind brushstrokes even if you drew them after the initial ones. Its a free app and fine for what it is.