Google has quite secretly been developing a new program called "Google Earth". Its similar to NASA's WorldWind program, but much better. With GE (Google Earth) i can zoom right into the town i live in. I can even see the school i used to go to, and even more amazing is that i can pinpoint my house and our car outside it!
Download it at http://desktop.google.com/download/earth/index.html
(Currently downloads are taken off due to traffic, but will be up soon)