GeoFusion offers virtual flythroughs of the Red Planet with datasets from NASA. Viewers can use mouse and keyboard to navigate to Martian features like Gusev and Karst. (You'll also need a video graphics card suitable for gaming.)

Using other free datasets, viewers can fly around Earth, reviewing the devastation wrought by the 2004 tsunami and Hurricane Katrina, tracking the receding polar icecaps, and landing on the continents of their choice. For a fee, the company will create custom flythroughs that you can show on your own Web site.