I've used the pullover for a long time as a drill to improve flexibility. Lay down on a bench, feet up in the air, reach back down toward the floor overhead with a weight in the hands and repeat keeping the arms straight and the shoulders down. I liked almost everything about this until just recently. Through putting together the Simple Shoulder Solution, it became very obvious to me that scapular movement is a HUGE, MASSIVE, TITANIC component to healthy functioning shoulders. This is why scapular movement is emphasized in a big way in the book.
When you are pinned down on a bench, however, these little guys don't get to move so well.
The solution seemed so obvious, it was one of those things, I smacked my forehead and thought, "why haven't I been doing this the whole time?"
Simply lay down lengthwise on a foam roller with the head and spine supported. You still get the extra ROM of being elevated, and the scapulae are now free to dance around at your control.
A couple key points to remember:
You can do the movement with a bar, plate, dumbbells, or compliant pet - just use the right tool for the job.
Higher repetitions tend to work better with this one. It's also a nice drill to mix in with or before handstands.