On my quest to find the end of the internet I found out about this 3d printing process. http://www.youtube.com/watch?v=s3gHHeD6cv8&feature=related I think with a very good survey of a complex cave you could produce a very neat 3d model of the cave that you could put on a mantle or bookshelf. It would no doubt be a coversation peice and you could always know that your favorite cave is right in your living room!
I know this clip shows a very expensive technique but i have seen cheaper more primitive versions. Let me know if you think this would be as cool as i think it would be!