Pinboard (marks) https://pinboard.in/u:marks/public/ recent bookmarks from marks A Week on Foursquare 2011-05-23T15:21:31+00:00 http://graphicsweb.wsj.com/documents/FOURSQUAREWEEK1104/ marks foursquare study research checkin data https://twitter.com/ https://pinboard.in/u:marks/b:53aab864b83d/