What the Dude said. I've used it on beef, pork, poultry, and fish with good results. My preference is to use it on the poultry and fish. I'll generally pick other seasonings for pork or beef, but the Old Bay works fine in a pinch.
Old Bay makes a rub for seafood but it really good on just about everything. I have been using it almost all the time on any kind of meat from ribs to butts and even seafood too. It's really good and not just for seafood. www.oldbay.com/Products/Old-Bay-Rub.aspx