I promised I'd post the results of my attempt to emulate the style of map in this image:

http://www.glennzilla.com/Maps/Fathusra_Wilds.jpg

Here is the PSD file I created.

http://www.glennzilla.com/Maps/Terrain_Test.psd

It's not meant to actually be a map just an attempt to demonstrate the techniques used. I used a heightmap similar to my previous tutorial (GlennZilla's Own Little World) and a lot of layer masks.

For example to paint the forest into place I used this brush



I simply created a green layer with some noise on it and painted with the brush on the Layer Mask.

Similarly I painted the areas to have the "pebbles" texture on a layer mask. The trick to getting the Texture layers to work right is to use a layer filled with black with the blending mode set to "Screen". This way only the white highlights added by the texture are visible. Conversely you could use a white layer set to "Multiply" to make the shadows visible.

I think it gives everyone a sense of how I did it at least. Now I need to look into incorporating this into my new world and cough up a decent regional map before D&D 4.0 is released.