Last week Microsoft spent $7.5 million to buy 666,624 what?

Answer: IPv4 addresses. The company purchased a block of the soon-to-be-extinct addresses from bankrupt telecom equipment builder Nortel. Few IPv4 addresses remain as the number of websites around the world continues to grow. A push to transition to IPv6 - and the 340,282,366,920,938,463,463,374,607,431,768,211,456 possible addresses it will make available - is a top priority for many in state and local government.