NASA WorldWind is worth a check.

“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.”

WorldWind uses Managed DirectX (MDX) to acheive this. But what caught my attention was /cfWorldWind, when I was reading Mike Hall's weblog. Managed DirectX 3D Mobile (MD3DM) can do wonders and this is a proof of it.

One of the screen shots of /cfWorldWind:

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