<http://schema.org/topics>
"digg,EyeTrackShop,Facebook,flickr,Google,klout,linkedin,pinterest,reddit,Social Media,stumbleupon,trending,tumblr,Twitter,Uncategorized,YouTube"^^<http://www.w3.org/2001/XMLSchema#string>
<http://mashable.com/2011/11/30/social-profile-eye-tracking/>