Snatch and Clean Extension: Be Patient
A big mistake with the snatch and clean is trying to initiate the final explosion too soon. This can create a list of problems, including shifting your balance too far forward, pushing the bar away from your body, preventing a complete extension of the hips, and limiting the speed and height of the bar. Bring the barbell back into your body as it leaves the floor, and continue using the lats to push it back into the hips - not near the hips, but actually into the hips. (Understand that the hips DO move forward toward the bar as well - however, the effort to move the bar back to the hips helps prevent the lifter from shifting forward as is the natural tendency, and from over-reaching the hips through the bar).
If the barbell never touches your body, you're doing something horribly wrong. (By the way, keep the bar in tight to the legs on the way up - if the bar is banging into your hips when it contacts, you've let it get too far away first.) When the bar is into the hips, you're balanced properly over the feet, and your shoulders are still over the bar, drive through the ground explosively and snap the hips open (or you can use the dirty little word jump). Do it right, and you will feel and hear the bar pop up for you faster than it ever has; additionally, you'll find your pull under and your balance in the receiving position much improved.