Cool... I am currently running an underground campaign(started underground) and they have found a "very" small exit... now they just need to find the methods of opening the "big" exit to get the humans, elves, dragonborn, and halflings out.... Of course... there are some "complications" to overcome first... D&D 4E and they are 4-5 level(I think one just hit 6th level). I use maptool and either a projector or TV, so in most cases, I use tiles and just "stitch" then together to form a layout I like for caverns...