Algorithm for orientation of a 2d vector?

Hey; I was wondering if there is a simple algorithm that takes an x and y value (the values of the vector), and returns the angle between north and the vector, clockwise? All that I learned in trig class back in school has left me, and Google isn't giving me anything useful.

why don't you take another vector that points "north" and then, liek, totally use trigonometry and shit?