I brine them in salty water overnight, then roast them medium to rare. (won't take long, maybe 8-12 minutes in a 400 degree oven) With divers I would recommend a sauce, like a red wine sauce or something with some bold flavor. Divers in general can be a tad fishy, and the one bufflehead I've eaten was good, just a little fishy. They're not teal.
I love all of God's creatures, properly prepared.