[Physioguy]

Sure, how about taking the medicine ball in both hands, stand on one leg, and reach the ball overhead and behind you (not straining or stretching, but getting back there a little), and bring it back in front of you. Repeat for a given period of repetitions or time.

For some "golfy" exercise, assume a golf address position, but holding a medicine ball where the golf handle would be. Repetitively perform some backswing movements, occasionally throwing the ball over your back (towards the target). Of course, you can also work the "follow through" part of the swing, this time occasionally throwing the ball towards the opposite direction (i.e. away from the target)

Key points would be to allow the weight to shift towards the backswing side, or the follow-through side, as appropriate. For the backswing exercise, try to FEEL the right side loading, for the follow-through, FEEL the left leg loading.