"Keyhole fuses high-resolution satellite and aerial imagery, elevation data, GPS coordinates, and overlay information about cities and businesses to deliver a streaming, 3D map of the entire globe.
The result is a whole new way of looking at your world - reach out and "grab" the earth with your mouse, pan quickly to your area of interest (or select it from a placemark) and then zoom smoothly down to an individual building. Watch as the city unfolds itself before your eyes, revealing new perspectives and fresh insights."
The movies alone are worth the price of admission (free), but if your system can handle it, I suggest trying the 14 day trial period (also free). The product itself is understandably pricey.