TechThe Fortune 500 social media starsThese companies outshine their peers on the likes of Facebook, Google+ and TwitterKurt WagnerMay 6, 2013General Motors - #7 Aflac - #118 Visa - #260 Facebook - #482 AT&T - #11 Caterpillar - #42 Oracle - #80 Safeway - #62 Coca-Cola - #57