Google Earth is a free download (for windows) that enables you to view the earth as a 3D object that you can zoom in and fly around. You can adjust the tilt and see buildings in 3D, fly to locations, it really is quite amazing.
Imagine a combination of Google Maps and Google Local in 3D. The search facilities can literally fly you anywhere on the map
It really has to be seen to be believed. If you've got windows and your machine's up to the spec take a look.