I'm starting to love Layar more and more. One of the latest "layers" introduced was the ability to view the Berlin wall - as if it was still standing - by pointing your phone to the place where the wall used to exist. You can read the entire article here.
Do you see the potential? Being able to peek at any historical time and place and see what that location looked like a long long time ago. Imagine going to the Coloseum in Rome, Italy and watching a 3D gladiator fight happening in front of your eyes. Granted, that will take more development in augmented reality contact lenses (which, believe me, will exist in a near future) but for now you can potentially do that with your phone.
I really have to get an Android powered device :)