Program: Google Earth (Powered By Keyhole)

Offical Home Page: http://earth.google.com

Download Required: Yes

Cost: Standard = Free, Commercial = $400

Available Versions:

Google Earth (The Free One!)
The idea is simple. It’s a globe that sits inside your PC. You point and zoom to anyplace on the planet that you want to explore. Satellite images and local facts zoom into view. It requires a connection to the internet as it streams in image data as you explore and zoom in on different areas of the globe. Fantastic user interface makes this an amazingly easy and fun tool to use. Hours of enjoyment.