OK, been working on the Terrain Map textures. Using the tutorial above and adding a few tweaks of my own, I've generated the below 3 maps. The first is an RGB map, the second the Bump map and the third is the reflection map (the 'bolts' are all white a very reflective!). The maps originally were created at 1024x1024, but I've reduced them here so you can better see them. I used the above Ambient Occlusion image as the top layer with an opacity of 60 and set to multiply, so only the dark areas show.