Ed Friedlander, M.D. is a doctor who writes about Shakespeare. I've linked to his stuff before. Recently his page on Enjoying Macbeth came up (which I don't think I've linked before) and it's worth a look for it's brutal description of the violence, if nothing else. He comes right out in the first page and warns people that it's not family entertainment, and goes on to not only point out every scene of violence, but to put them in proper historical context. Yet he still keeps it very accessible, even pointing to oddities like why no one suspects Lady Macbeth, even when she comes out with her "What, in our house?" line. Methinks the lady doth protest too much! Wait, wrong play.
Anyway, lots of great info on that page, far more than most I've scene. Worth checking out.