1) Some sort of distorted reality map, like the the Netherstorm map in WoW (YES I KNOW AND NO, I don't want to turn this game into WoW -.-). Or any map located in the Outland, actually.

2) It'd be nice to have a full map inside a mountain or under the earth, with caves systems interconnected, buried temples, inner lakes, access to a magma core with a system of bridges.

3) Same concept than 2 but underwater.

4) A deep pure jungle.