Beyond RPGs there are, of course, videogames and literature.
I've seen a couple of "pros" on here that have done things like visitor maps for theme parks and such. One guy posted a couple done in Illustrator along with videos showing the process (it was awesome to watch, BTW). I would think that sort of this would be pretty common - tourist maps, visitor maps, etc. Less artistic would be the folks that do escape plan diagrams, "you are here" maps, and that sort of thing.
I'm not immediately calling to mind other applications. Anybody else think of anything?