Would I sound like a smartass if I said turkey and cranberry sauce? Great thread, its nice to actually think about bitterness as something other than "bad" or a problem to get around. Turnip has a distinct, if mild, bitter flavour, that has always been used to balance stews, braises, and the like.
I keep hoping that bitter will become the new "spicey" in North American cuisine, something a little daring for a while, then common.
--Al