Within the CKC (Collaborative Knowledge Construction) Challenge, several tools for collaboratively creating structured knowledge were compared. The results have now been described in a free available IEEE Intelligent systems publication that can be downloaded here.

A more detailed technical report can also be found here.

The two publications at least provide a decent overview and classification of six tools for the collaborative creation of structured knowledge (e.g. taxonomies and lightweight ontologies).

(Source: Valentin's Blog On Artificial Intelligence and Web Science)