flickr is promoting photos in what it calls "The Commons", but only to logged in users. Normal users (who can't comment / tag the photos in the commons anyway) don't get an obvious link to them (except via about a billion third party sites such as blogs and google search). The page also shows how the national library's choice not to include text in their logo has come up trumps.
The confusingly similarly named "The Commons" and "Creative Commons" parts of the website apparently don't reference each other. Odd.