In Iceland, rarely do people take the last name of their spouse, male or female. This is because you take the name of your (usually) male parent and stick 'dottir' or 'son' to the end depending on your gender. Therefore a girl named Hanna Jonsdottir is, surprise, the daughter of a guy named Jon, and her brother's last name would be Jonsson.
Not surprisingly, many an Icelander has had trouble traveling abroad with their families, since usually everyone has a different last name.
(By the way, everyone's listed in the phone book by their first names... including the Prime Minister)