I still can't imagine or believe it will ever be possible to really use it, but Microsoft new preview of Photosynth is still one of the coolest thing I saw recently.
Basically what Photosynth does, is taking tens or hundreds of photos of the same place, examine them, and build a 3D model of the place.
Now you can browse the photos in a really cool way, letting you explore the place and get the feel of how it really looks in reality.
You need a good video accelerator (and good bandwidth) in order to enjoy it, but I really recommend you checking it out.