The Stength of Weak cooperation: A Case Study on Flickr
  Web 2.0 works with the principle of weak cooperation, where a huge amount of individual contributions build solid and structured sources of data. In this paper, we detail the main properties of this weak cooperation by illustrating them on the photo publication website Flickr, showing the variety of uses producing a rich content and the various procedures devised by Flickr users themselves to select quality. We underlined the interaction between small and heavy users as a specific form of collective production in large social networks communities. We also give the main statistics on the (5M-users, 150M-photos) data basis we worked on for this study, collected from Flickr website using the public API. 
Christophe Prieur (LIAFA), Dominique Cardon, Jean-Samuel Beuscart,   Nicolas Pissard, Pascal Pons (LIAFA)