I've just made the best bread ever at home in the bread machine, and everyone present agreed (though at first no one would try it). It was the standard white bread recipe, but for the liquid ingredients, it was about half Young's Double Chocolate Stout (warmed up in the microwave), and half milk.
Gotta go to Trader Joe's and stock up...
Update: It also comes out well with one of the three cups of flour called for in the recipe being wheat flour.
Another update: Although Guinness will do in a pinch, it's definately better with the chocolate stout.