When working with the transform tools (move, rotate, & scale) you can constrain transformation along a single axis by left clicking the axis handle you want (it will change to yellow), then click and drag the middle mouse button to make your transformation.. This offers two benefits. First you don't have to be right on the manipulator handles in order use them and in the case of rotate handles will allow to spin more since you can drag across the entire screen and not just to the manipulator limits. Try it out for yourself