Richard Branson
Richard Bransons catamaran, the Necker Belle, can go as fast as 20 knots. It can host around 10 people at a time and is actually available for rent for around $110K a week... pocket change.
Johnny Depp
Johnny Depp joined the island-owner club when he purchased Little Halls Pond Cay in the Bahamas for $3.6 million. We're not quite sure what his plan were for the little oasis, but when you're Johnny Depp, do you really need a reason?