In Web 2.0 users not only make heavy use of Collaborative Information Services in order to create, publish and share digital information resources - what is more, they index and represent these re-sources via own keywords, so-called tags. The sum of this user-generated metadata of a Collaborative Information Service is also called Folksonomy. In contrast to professionally created and highly structured metadata, e.g. subject headings, thesauri, classification systems or ontologies, which are applied in libraries, corporate information architectures or commercial databases and which were