PhotoSynth

Great piece of software, you have to try it. SO what's PhotoSynth:

Photosynth is an amazing new technology from Microsoft Live Labs that will change forever the way you think about digital photos.

Our software takes a large collection of photos of a place or an object, analyzes them for similarities, and displays them in a reconstructed three-dimensional space.

The Photosynth Technology Preview is a taste of the newest - and, we hope, most exciting - way to view photos on a computer. Our software takes a large collection of photos of a place or an object, analyzes them for similarities, and then displays the photos in a reconstructed three-dimensional space, showing you how each one relates to the next.

In our collections, you can access gigabytes of photos in seconds, view a scene from nearly any angle, find similar photos with a single click, and zoom in to make the smallest detail as big as your monitor.

The input for the demo were thousands of photos of Piazza San Marco grabbed from Flicker.
It's a pity we can't input our own photos yet...