Hell yeah!
Thanks to the wonders of cable On Demand I've recently re-watched every episode of the first four seasons (Netflix has them too I believe). Mad Men is the only show I re-watch episodes of, as I notice something new every time.
One of my favorite moments is from episode 6, season 3, when the pretentious English prick gets his foot run over by the John Deere. It was just so shocking in a show that never featured any real gore before. As sick as I am, I still laugh my ass off every time I see it.