What is the point of a bullpup?

I'm not looking to "debunk the myths" surrounding bullpups, I really want to know why one would be used over a standard layout. I'm not much of a rifle guy (pistols and shotguns are my main thing, and even then I favor handguns), but I see bullpups used in military and policing and also in competitions and sport shooting. What is the advantage of a bullpup? Why would I choose one?