In OD&D, one-quarter of all "magic items" consist of treasure maps. This percentage is reduced to one-tenth in AD&D, but that's still sizable. If you've ever wondered about the origin and purpose of the read languages spell, look no further than treasure maps: "the means by which directions and the like are read, particularly on treasure maps."
"A cloak of elvenkind is of a plain neutral gray which is indistinguishable from any sort of ordinary cloak of the same color. However, when it is worn, with the hood drawn up around he head, it enables the wearer to be nearly invisible, for the cloak has chameleon-like powers. In the outdoors, the wearer of a cloak of elvenkind is almost totally invisible in natural surroundings, nearly so in other settings. Note that the wearer is easily seen if violently or hastily moving, regardless of the surroundings."