Flickr

Wikipedia article

Flickr has been created in 2004 and has become very popular in research due to its social networks (users have friends, can join groups etc.) and its social bookmarking facilities (users can upload and tag photos, geotagging functionality etc.). More then 4 billion photos have been uploaded since its creation and the Flickr API (http://www.flickr.com/services/api/) makes the data accessible.

Related papers

A list of interesting papers to give an impression of the wide range of research topics using Flickr as dataset:

• Towards Automatic Extraction of Event and Place Semantics from Flickr Tags (SIGIR 2007) This paper investigates the task of determining if a tag represents an event or location. They use photos (and the corresponding tags) which have geotagging metatadata (location and time of photo). Their intuition is that these tags occur as burst in time or location.
• A Measurement-driven Analysis of Information Propagation in the Flickr Social Network (WWW2009) This paper examines the popularity of photos on Flickr (photos often marked as favorite). They analyze how fast popularity spreads, what the influence is of the social network and how widely popularity spreads.
• Growth of the Flickr Social Network (WOSN 2008). This paper explores the social network of Flickr. They investigate reciprocation, preferential attachment and proximity bias in link creation.
• Flickr tag recommendation based on collective knowledge (WWW2008)