To be a bit more specific on the tri-tip, it is part of the sirloin and if you look at the beef photo dc posted and look at the bottom right corner of the bottom sirloin (pink section in the pic) that piece of sirloin that is triangular shaped that separates the flank from the round is the tri-tip. The whole piece is triangular shaped and can be left as a roast, or cut up into tri-tip steaks. I believe this cut of beef was "invented" in California a few yrs ago and has slowly been making it's way around the country. I do not see it at any local butchers here in Michigan, but I do see it in the meat departments of the big chains such as Kroger, Meijer, and Wal-Mart.
Pulling my pork....200 lbs at a time!!