Umpires often blow calls. But Joyce's wrong call at first base nixed pitcher Armando Galarraga's chances of a perfect game. Those don't happen often. Even rarer: Joyce apologized.
For connecting more than half a billion people and mapping the social relations among them, for creating a new system of exchanging information and for changing how we live our lives, Mark Elliot Zuckerberg is TIME's 2010 Person of the Year
4. Jim Joyce