overhead flexibility question

I've been olympic lifting for about a year now and have found I am lacking on the overhead shoulder flexibilty when I snatch which in turn is hurting my hip flexibility. I tried looking in the archives for a some good streches for my shoulders but I cant seem to find anything.

I have no problems squat cleaning or jerking but when I go to snatch I've found my shoulders wont rotate far back enough which really limits the amount of weight I can get up because I catch and balence in the bottom position so I tend to lose the weight forward. Any sugestions?

 

http://www.youtube.com/watch?v=dNilld58tks

 

practice practice practice

I started using a broomstick and doing overhead squats, eventually working into a weighted bar, and I use kettlebells which seemed to loosen up my shoulders a good amount over time