I read somewhere that lutes used to be made with strings that just picked up the vibrations from the strings that you played to give a better tone. I don't know how these things were built though, I think lute is just a kind of dustbin term for guitar like instruments.
As for exotic instruments what about a chapman stick or a war guitar. They're many stringed bass/guitar hybrids designed for people who are demons at tapping, cost masses of money but are seriously cool. I know King Crimson played with them in the early 80s.