Daniela Barbosa, who is the business development manager for Synaptica at Dow Jones Client Solutions has written a fabulous eBook explaining how to mix taxonomies built by professionals and folksonomies, which let users tag content as they see fit
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.
Y. Yanbe, A. Jatowt, S. Nakamura, and K. Tanaka. JCDL '07: Proceedings of the 2007 conference on Digital libraries, page 107--116. New York, NY, USA, ACM Press, (2007)
A. Hotho, R. Jäschke, C. Schmitz, and G. Stumme. Proc. First International Conference on Semantics And Digital Media Technology (SAMT), volume 4306 of LNCS, page 56-70. Heidelberg, Springer, (December 2006)
R. Jäschke, B. Krause, A. Hotho, and G. Stumme. Proceedings of the Second International Conference on Weblogs and Social Media(ICWSM 2008), AAAI Press, (2008)
M. Grahl, A. Hotho, and G. Stumme. 7th International Conference on Knowledge Management (I-KNOW '07), page 356-364. Graz, Austria, Know-Center, (September 2007)
A. Hotho, R. Jäschke, C. Schmitz, and G. Stumme. Proceedings of the First Conceptual Structures Tool Interoperability Workshop at the 14th International Conference on Conceptual Structures, page 87-102. Aalborg, Aalborg Universitetsforlag, (2006)
W. Jones, A. Phuwanartnurak, R. Gill, and H. Bruce. CHI '05: CHI '05 extended abstracts on Human factors in computing systems, page 1505--1508. New York, NY, USA, ACM Press, (2005)