<http://schema.org/topics>
"blurb,Business Lists,CafePress,CDBaby,createspace,design,DeviantArt,imagekind,Lists,lulu,pikistore,Ponoko,print on demand,sell products,Shapeways,spoonflower,Spreadshirt,tastebook,the game crafter,Zazzle"^^<http://www.w3.org/2001/XMLSchema#string>
<http://mashable.com/2009/09/05/sell-products-online/>