Yahoo Terms Extraction
http://www.jluster.org/2005/04/updated-y-terms-extraction-plugin/
Jonas Luster over at jluster.org is working on a WP plugin to extract terms using the context feature on Yahoo's API. I'm keeping an eye out for his finished plugin and see about using it on my domains.
Another article about the Y! service and it's good and bad points at:
http://theryanking.com/blog/archives/2005/04/10/tags-and-term-extraction/