yes, Hams, Glutes and lower back, this is the posterior chain, and this is what good mornings works on.
And are you kidding about rolling the bar over your head to get rid of it???
Only, and I mean only do these with a competent spotter on each side, or better yet, as I do, do them in a power rack with the catch pins set up so you don't kill yourself.
I am not close to being the strongest guy on this board, but I have gone up into the mid 400's on good mornings. Rolling the bar over your head to get rid of it would be a good way to get a permanent reverse mohawk. I can just imagine how long it would take to grow hair back on the middle of my head if 435 lbs worth of knurled bar rolled over it.
I would not recommend going completely to parallel either, unless with a relatively light weight. When things start getting heavy for me (over 315) form gets a little dicey, but as Dave Tate says, when the weights get heavy, just get the damn thing up.
B.