Cable pullovers allow for a great stretch and full contraction of the lats. The added benefit of having your entire back supported by lying on the ground lets you focus on volume without the fatigue accrued by supporting yourself.
Remember, big lifts first, then do this low-stress finisher for added volume.
A while back here at T-Nation, I released a series on what I called Pendulum Training. This is basically a training system that has you switching from structural training to functional training every week.