WorldWind [NASA sw]

Here's a program that lets you roam over Earth as if from a satellite. It's called World Wind from NASA - a free and beautiful program - here's the link:
http://worldwind.arc.nasa.gov/

It's a fabulous program, letting you move over the earth's surface and perform virtual flybys. But it's a bear: The download is 180mb and requires 2GB of disk space, a decent/recent 3d video card, and you must be
running both .NET and DirectX.

It also needs a pretty fast connection when it's running: "World Wind comes with data you can zoom into. After a certain point, World Wind will begin to download more images automatically."

So---yes, it's a great tool, but it's *very* demanding software. As long as you're OK with that, you'll love it!