Over the two weeks, the CKC Challenge Web site had visitors from over 60 coun-tries. User activity peaked during the last three days. Forty-nine users registered for the challenge, of which 33 actively partici-pated. Over 50 percent of those 33 tried only one tool. We received 36 feedback forms: 31 tool-specific and five general forms.
Soboleo had the highest user activity, with 65 percent of the active users trying it (see figure 1). Users seemed to prefer one type of system over another. The tools represented a range of functionality-SoBOLEO and BibSonomy focus on annotating re-sources, such as Web pages and bibliography entries, while the other tools focus on building structured data and ontologies. So it makes sense that users who tried Soboleo also tried BibSonomy, and users who tried Collaborative Protégé also tried OntoWiki. For those who used more than two tools, the two tools they used most were of the same type.