FLICKR
According to wikipedia, "Flickr is a photo sharingwebsite and web services suite, and an online community platform, which is generally considered an early example of a Web 2.0 application.
In addition to being a popular Web site for users to share personal photographs, the service is widely used by bloggers as a photo repository. Its popularity has been fueled by its innovative online community tools that allow photos to be tagged and browsed by folksonomic means. Tagging is a key aspect of Web 2.0. You can give your photos a "tag", which is like a keyword. Tags help you find photos which have something in common. You can assign up to 75 tags to each photo.
Flickr has a repository that is quickly approaching 1 billion images (as of August 2007).
Folksonomy (also known as collaborative tagging , social classification, social indexing, social tagging, and other names) is the practice and method of collaboratively creating and managing tags to annotate and categorizeContent. In contrast to traditional subject indexing metadata is not only generated by experts but also by creators and consumers of the content. Usually freely chosen keywords are used instead of a controlled vocabulary.
Folksonomies became popular on the web around 2004 with social software applications such as social bookmarking or annotating photographs. Websites that support tagging and the principle of folksonomy are referred to in the context of Web 2.0 because participation is very easy and new tagging data is used in new ways to find information. For instance tag clouds are frequently used to visualize the most used tags of a folksonomy. The term folksonomy is also used to denote only the set of tags that are created in social tagging."
