http://en.wikipedia.org/wiki/P-38_can_op...
A nail clipper is about as simple as it gets. It depends on the definition of a machine versus a tool. Simple tools include a pry bar (which operates on essentially the same principle as a nail clipper - the use of a lever to exert a higher force on one end than on the end of application).
A basic pulley is a simple machine.
A lever. Because it provides a mechanical advantage.
a stapler
