When all of the augmented reality apps started shipping for the iPhone, I started thinking of the most useful applications of the concept. While it's entertaining to see subway stations all around you, I have a harder time remembering people.
I want an app where you can hold your iPhone up and point it at a group of people, it will recognize the faces of those in your contacts list (iPhoto already has facial recognition) and show their names. You would also be able to go back and look at previously taken photos to see who is in them for a reminder. And maybe, in some future world where privacy concerns aren't an issue, I'd be able to see the names of friends of friends with links to some of their profiles on the web.
Writing this, I remembered I thought of something similar for DVDs. Then I found this Nokia video below (via Nick Bilton) that shows something pretty similar to the app I want. I do like Nokia, but it's funny they're calling this the technology of 2015 when we could probably do this today.