What causes the variety of autumn leaf colors?

I know that the fall leaf colors are due to the residual of the leaf that is present after the phototsynthesizing cholorophyl goes away. But why is there such a variety of different colors? Not that I am complaining.

The colors come in various shades of yellow, orange, red and brown and each tree species seems to have its own specific color. Unlike flower colors, I doubt that the colors have any significance on their own. I would suppose that just as chlorophyl makes leaves uniformly green, whatever is left over must serve some purpose and therefore should have a characteristic color.