Dutch advertising agency Gummo, the Netherlands Architecture Institute (NAI) and TNT Post present the first stamps in the world with augmented reality. The stamps show five unbuilt works by famous Dutch architects. Each stamp is printed with a unique QR-code that when placed in front of a webcam erect 3D buildings in the palm of your hand. By moving the stamp, users are able to see the virtual building from almost any angle.
The whole stamp sheet also yields an image of the NAI itself, when held up to your webcam.
The project also created a great iPhone app that lets you hold your phone up to a site and see what a wildly experimental, unbuilt design could have been.