I had just happened to watch a few youtube tutorials from Dave Tate on the deadlift before I head over to the gym for my deadlifting session yesterday. In it, he talks about dropping your shoulders forward as you ascend to the bar which naturally puts a little rounding in your upper back.
I was sure to have someone watch my lumbar spine for any signs of lumbar flexion and managed to keep my lower back arched. I was quite pleased with the feel of dropping my shoulders forward as it let me set up with my head a good 3 inches higher and I had a much more powerful drive on the motion, taking alot of the feeling off my lower back and into my quads, hammies, and glutes.
Any way, I thought I'd share, and I'm happy to discuss what you guys are doing.