We've been talking about weapons, but I think I should mention paper armor. Appatently in medieval china they found that you could make functional armor out of half inch thick tiles of folded heavy-duty paper. It's efficacy was tested on an old episode of Mythbusters and they found that it performed as well as 1/16 inch steel armor against slashing and piercing weapons, although it didn't do jack against bludgeoning weapons.
(Now that I think of it, that would be a good way make different armors more distinct in RPGs - give them a different armor class against different kinds of weapons)