For some reason, the town of Portsmouth in England - a major naval base for centuries - has the nickname Pompey; as does its football club. Not a bearer of the name, exactly, but certainly famous.
Urg, as someone has said before, Pompey is pretty widely known as a nickname for Portsmouth here in the UK -- not something you'd want to name your child (unless you really, really liked the football team). Besides, it sounds awful, and a lot like "pompous".