Q: "What happens if we run out of hurricane names?"
A: If we're unlucky enough to deplete the year's supply of names we won't, contrary to popular opinion, simply start using names from next year's list. In that case, the National Hurricane Center will turn to the Greek alphabet and we'll have Hurricanes Alpha, Beta, Gamma, Delta, etc.
http://miami.about.com/od/weather/a/hurricanenames.htm