NASA World Wind
Have I ever lied to you? I didn't think so. Therefore, you MUST believe me when I say that this program is the coolest thing to hit your computer. If you've ever read Neil Stephenson's Snow Crash, you will recognize this. In the novel, there is a program called Earth, which provides a real-time, fully-zoomable rendering of the Earth's surface down to a resolution of a few meters.
Re-read that sentence, and omit the word real-time (we don't have the satellite bandwidth yet) and maybe slack the res off a bit, and you have
NASA World Wind. Straight from the horse's mouth:
World Wind lets you zoom from satellite altitude into any place on Earth. Leveraging Landsat satellite imagery and Shuttle Radar Topography Mission data, World Wind lets you experience Earth terrain in visually rich 3D, just as if you were really there.
Virtually visit any place in the world. Look across the Andes, into the Grand Canyon, over the Alps, or along the African Sahara.
They speak truth. If you have any allusions of having any sort of geek cred, go download this and at least play for a minute. Just find the place where you live. That's it. If it doesn't sell you, nothing will.