With an estimated net worth of $17.5 billion, Microsoft cofounder Paul Allen can afford some expensive toys. His 414-foot yacht, "Octopus," has to be one of the best billionaire toys around.

"Octopus" is believed to be the fourth largest yacht in the world only behind the ... club with M/Y Pelorus and M/Y Le Grand Bleu. Paul Allen who is rated the third richest US citizen and seventh ...