I'd seriously considering using the Wilbur Method on my section of the Big Idea Map. Unfortunately it's pretty destructive of existing structures, so I could probably never get my map to fit back in with the neighbors. Everybody would laugh at me... throw rocks and garbage... I don't know. For an original map, though, that kicks serious booty.

There's some stuff I've been doing with grunge brushes with some success. It's pretty hit-or-miss, though. Even more than some of my other off the wall ideas. Also, I don't trust PS to paint in 16-bit.