Give it an address, any address, and it will give you a plane's-eye view. We had pictures of our house taken in 2002, and then of the area our house was in in 91. Even lets you move around, like a giant Yahoo map. Freaky!
This is definitely neat - when I look at our place there wasn't even a road on the '81 topo map and our buildings weren't built in the '88.
Have you tried www.keyhole.com?
it's terraserver + aerial photos + 3D graphics + maps