Is there a good program to do large-scale rpg mapping for OSX? I know of dundjinni, but some people here have mentioned that it is rather poor at global or continental scale modeling.
You could try RPGMapMaker, but I know you can get much nicer results with Dundjinni.
What DJ can or can't do is entirely dependent on the artwork you put into it. Take a look at the Campaign Art Pack, for example: http://www.dundjinni.com/art/user_art.asp