Of course it does. It depends on what you plan on going into - I'll be going into applied/computational in the fall, and my CS minor will no doubt be a benefit ( I assume ). However, I believe that people of all fields would also benefit from a hearty dose of CS / programming.
Unless you plan on going pure math, you should try to minor in the field which your intended area of graduate study slants towards ( bio, physics, cs, chem... ). I'm not sure what a pure math person would minor in if anything. philosophy?
Of course there's always underwater-basket-weaving to consider as well.