Some kind of Legend of Zelda Map? You could remake a town from one a game, say, Ocarina of Time, or one of the temples, and put in some traps and things.
A Minecraft map that would actually work and be big enough for play? (Just a suggestion).
Nuclear Power Plant? (Complete with nuclear waste pools/traps!)
A Clue Map actually based on the Original Clue Version Game Board.
I think he's looking to add specific maps to his server, not create his own.