Thanks guys, but honestly, it's a lot simpler than it looks - anyone can do it. I think we get so hung up on using textures that we forget that you can actually get a reasonable map done much faster by just using a round brush in photoshop or gimp and playing with the brush settings.

I'll try to do a video tutorial for this. It's really quick to do. The only bit which requires any artistic knowledge / talent is the mountains and as you can see from them, I really don't have much of that, but I'm sure if I fiddled with the mountains for a couple more hours and looked at references I could have got something more decent.