I have CIPA Custom towing mirrors which just slide over your original mirror housing, so you have your original mirrors and the additional independently adjustable mirror. They don't look bad either.
http://www.aztrucks.com/category.asp?product=80 will give you an idea what they look like. I bought mine at our local ACE Hardware, but Schucks also had them, just not the one I needed. Cabela's also has them for about half again the price! Maybe their's are made of gold instead of plastic.