Dvorak v. QWERTY.

QWERTY is only used because its common. Its one of the most inefficient designs. We only think it is efficient because we learned to use it first. Its like how Americas prefer English or our crappy measuring systems are only considered easy and efficient because we learned them first.

Edit: I should also mention that QWERTY was designed for typewriters and it's design was meant to slow the typist down. Since Typewriters didnt allow you to erase mistakes and edit your paper, slow typing was important.