Jamie and Arden-
I've be focusing on cleans and snatches quite a bit lately, and have learned a couple things-
box jumps and tall cleans/snatches are excellent for training you to close your hips, and get your heels to your butt fast. Also, doing tall cleans, I FINALLY felt it when I used my arms to pull myself under the bar. It reminds me of swinging under bars on the playground when I was little.