I have a cousin whose driver's license name is "FNU" which stands for first name unknown. This was due to some quirk in his immigration documents. I cannot imagine how much havoc this must cause.
Oh man, there's this really good Radiolab episode (Null) about weird name stuff in databases. One story they got is from a guy who made his license plate NULL thinking it would be able to avoid tickets, but it ended up being the other way around.