Since the 1930s, IBM has not only created adding machines, computers, and the like, but also collected them. They apparently have an amazing historical collection of "counting and reckoning tools and devices," some of which can be checked out online. Joel has the details over at Boing Boing Gadgets. Seen here is a Hahn Calculator from 1774. It could multiply, divide, add, and subtract up to values with 12 digits. "IBM's 'Antique Attic' Gallery"