Okay, I'm a former pub waitress and here's the scoop. Black and tan, usually Guinness AND either Smithwick's or Bass, depending on availability, and customer preference. A Snakebite is lager, such as Harp, with cider. Strongbow and Black Sheep are 2 excellent imports. Half and Half has to be a stout and a lager, for example Guinness and Harp. The Stout floats on the lager. Finally, Black Velvet... Originally Stout floating on Champagne, but now usually Stout and Cider. All of these should be poured properly (the stout over a spoon) and you should see the line between the two in the glass.