<http://schema.org/topics>
"digg,Facebook,features,Foursquare,geo-location,Google,How To,Lists,Mashable,Social Good,Social Media,social networking,Twitter,year in review,YouTube"^^<http://www.w3.org/2001/XMLSchema#string>
<http://mashable.com/2010/12/26/social-media-resources-2010/>