BibSonomy is a system for sharing bookmarks and lists of literature. When discovering a bookmark or a publication on the web, you can store it on our server. You can add tags to your entry to retrieve it more easily. This is very similar to the bookmarks/
P. Heymann, G. Koutrika, and H. Garcia-Molina. WSDM '08: Proceedings of the international conference on Web search and web data mining, page 195--206. New York, NY, USA, ACM, (2008)
B. Krause, R. Jäschke, A. Hotho, and G. Stumme. HT '08: Proceedings of the Nineteenth ACM Conference on Hypertext and Hypermedia, page 157-166. New York, NY, USA, ACM, (2008)
M. Blank, T. Bopp, T. Hampel, and J. Schulte. Good Tags - Bad Tags. Social Tagging in der Wissensorganisation, page 85-97. Münster, New York, München, Berlin, Waxmann, (2008)