They aren't called anything...to my knowledge, if you find a name, please tell me @Illusion - Have you seen Sin City? Like where that chick is walking in the alley and her eyes are blue but everything else is black and white? That's what he means
Actually, B&W with only one other color is known as monochromatic. B&W alone is called monochromatic as well, but it can include one other color.