I have been working out a style for myself to use in Photoshop with a goal similar to this map.

It looks like the mountians are a combination of displacement mapping (Either with the displace filter or a bevel layer blending style) with the "metal landscape" texture applied to another layer just above it.

I was stuck trying to get the forests to looke the way I wanted, and now I've got the idea.

I'll tinker a bit and see what I come up with.