I did have a look at Don's tutorial (fantastic, btw) cos I wanted to do a city map for my campaign. I couldn't get the buildings to work as I wanted them though, so the map really started out as an exercise on how to do buildings. That's why I made the buildings pattern. The rest I made up from scratch except the dirt texture - can't remember where this came from, probably RPtools Dorpond or another.
The water effect is shown here in the RPtools forum:http://forums.rptools.net/viewtopic.php?t=2103
I think the poster edges filter (the idea of which did come from Don's tut) is a love it/hate type of thing. Personally I like it, but I can see why others might not.
Edit - forgot to mention that the different building colours are simply several hue/saturation adjustment layers arranged in a clipping group with the building pattern and then manually painted to colour random buildings.