Google Earth

If you though Google maps were fun, try Google Earth. It often has
higher resolution than the maps and you can tilt your view into 3D.
Once in 3D, pull with your mouse and then let go and you can fly
over/through the terrain.

Hands down, the best view of the world yet. Can't wait till we can
link flight sims up with it. In much of the US view you can see down
to small bush details on the ridges. Some of the rest of the world is
not so detailed.

Tim