ConceptNet is a freely available commonsense knowledgebase and natural-language-processing toolkit which supports many practical textual-reasoning tasks over real-world documents right out-of-the-box (without additional statistical training) including
M. Paolucci, T. Kawamura, T. Payne, and K. Sycara. The Semantic Web -- ISWC 2002: First International Semantic Web Conference, Sardinia, Italy, volume 2342 of Lecture Notes in Computer Science, Springer, Berlin, (2002)
Y. Gil, and V. Ratnakar. Proceedings of the 15th International Florida Artificial Intelligence Research Society Conference, page 413--418. Menlo Park, CA, AAAI Press, (2002)
S. Bechhofer, R. Volz, and P. Lord. The Semantic Web -- ISWC 2003: Second International Semantic Web Conference, Sanibel Island, FL, USA, volume 2870 of Lecture Notes in Computer Science, Springer, Berlin, (2003)
B. Grosof, I. Horrocks, R. Volz, and S. Decker. WWW '03: Proceedings of the 12th International World Wide Web Conference, Budapest, Hungary, page 48-57. (2003)