Eneroth3 has made some wonderful plugins for SketchUp. It is amazing to see what she has done as a programmer. This past Fall she put out a new plugin called Fractal Terrain Eroder. It subdivides terrain and then “crunches” it down to create a much more varied terrain. In the end the terrain looks more natural and it doesn’t take much time for the user to create it. And the plugin in listed in the SketchUp Extension Warehouse so it is easy to load. Try it out!