Table 1.

The Challenge tools and their descriptions. Detailed descriptions of all the Challenge tools are available in the CKC workshop proceedings [15]

BibSonomy	A web-based social resource-sharing system allows users to organize, tag, and share bookmarks and bibliographic entries	University of Kassel, Germany
Collaborative Protégé	An ontology and instance editor with additional support for collaborative development (history, annotations, discussions, etc.)	Stanford University, US
DBin	An application that enables collaborative editing of knowledge bases. The CKC brainlet contains an ontology and instance editor and discussion facilities.	Università Politecnica delle Marche, Italy
Hozo	An ontology editor that enables asynchronous collaborative development	Osaka University, Japan
OntoWiki	An ontology and instance editor that provides collaborative capabilities, such as history and ratings	University of Leipzig, Germany
SOBOLEO	A web-based system that supports annotation of web resources and creation of taxonomies	FZI Research Center for Information Technology, Karlsruhe, Germany