We've only known the name of Potter six for a few days but most of the online domain names for the Half Blood Prince have been snapped up already.
In the past, famous people have been locked in legal battles with net-users who nabbed domain names which they considered to be rightfully theirs.
But JK should have no trouble - many Half Blood Prince domains have been bought by firms she's connected to.
Potter film-makers Warner Bros have got harrypotterandthehalfbloodprince.com