I went out with some friends to the fabulous North River Tavern a few weeks ago and tried a new seasonal stout, Ommegang Chocolate Indulgence. It was tasty but wow, expensive.
It is yummy, sweet, and chocolately with a long (but good!) aftertaste. It has absolutely no bitterness. And it was bad for hangovers. I think most dark beers are. I recommend it anyway.