So the map you reference is by MarkusTay. His maps are created by creating brushes from the original Faerun maps - and that's not necessarily a good idea

This is a style created for the 3rd edition realms map. The cartography credits are Todd Gamble, Rob Lazzaretti and Dennis Kauth. I've tracked down both Rob and Todd's websites and neither have maps in quite that styke, so I have to assume the original was by Dennis Kauth. He doesn't have a website and seems to have fallen off the face of the earth a little. I believe all the lines are hand drawn in PS on one layer, and then a separate layer (or collection of layers) are used for a light watercolour fill. The original map in this style is here: http://www.wizards.com/dnd/images/wd...rLarge_150.jpg