My husband has a first name. I've seen his birth certificate, so I know what it is, but I don't use it. I usually call him "honey" or some other term of endearment. Lately, especially if we're working on a project together, we call each other "Louis" and "Billy Ray". It comes from the movie Trading Places, where, at the end, Eddie Murphy says "Looking good, Louis" and Dan Aykroyd replies "Feeling good, Billy Ray".
My son had a variety of nicknames when he was younger, but we don't use them much anymore. "Junior" is the only one that really stuck, although he isn't actually a junior. My daughter, on the other hand, responds to at least a half dozen different nicknames, including a shortened version of her given name. Most of the time, though, I call her "Peach" and I have since she was a baby. Recently, she decided she should have a fruit related nickname for me, so she's been calling me "Nectarine".
Of all the nicknames I've ever had, Willoughby is one of my favorites. It suits me. I look like a "Willoughby", don't you agree?