Combine Google Earth with Google Sketchup to do some amazing designs and win cool stuff. You are now able to import a 3D site from Google Earth into Google Sketchup. This means you could import the Grand Canyon and then design a bridge using Sketchup. The best part is that you can then send your model back into Google Earth and have the world look at your design. Fun stuff! You can even win prizes using these tools, check out this site: http://lineofsite.info
This method can also be used to get sites into AutoCAD, Revit or Civil 3D!