Calais is a rapidly growing toolkit of capabilities that allow you to readily incorporate state-of-the-art semantic functionality within your blog, content management system, website or application.
In this website you can find information about folksonomies, their strenghts and weaknesses, and Sem4Tags an approach to improve multilingual folksonomies using semantic web techniques. In addition, there is information about the developed demo software to associate tags with semantic entities.
A. Hotho, R. Jäschke, C. Schmitz, and G. Stumme. Informatik 2006 -- Informatik für Menschen. Band 2, volume P-94 of Lecture Notes in Informatics, Bonn, Gesellschaft für Informatik, (October 2006)Proc. Workshop on Applications of Semantic Technologies, Informatik 2006.