<http://schema.org/thumbnailUrl>
<http://cdn1.tnwcdn.com/wp-content/blogs.dir/1/files/2011/06/dropbox-520x245.jpg>
<http://thenextweb.com/apps/2011/06/29/save-files-from-the-web-to-dropbox-with-just-their-urls-using-sidecloudload/>