With the Heightmap Browser there is a powerful heightmap viewer available. It allows you to find real world locations as heightmaps and easily export them to Photoshop. Of course there are also other heightmap viewer on the web – take a look at the resource link list in the instructions PDF and online documentation. The 3D terrains created from the heightmaps can also be textured with Google textures or Open Streetmaps, for example. The results are really stunning!