Now this is cool. Tagyu is an “auto-tagging” service of sorts, created by Adam Kalsey. You paste in some text (or submit via their REST API) and it suggests tags, using some kind of a similarity metric between your text and already tagged texts in Tagyu’s index (gathered from del.icio.us etc.).
So far, I’ve tried a few different texts, and about half the time the returned tags are great. This is impressive, because this is not an easy problem to solve, but 50% precision is not quite enough for prime time. If someone (sploggers?) unleashes Tagyu to auto-tag a large volume of posts that feed back into the del.icio.us and Tagyu system, that would be detrimental to improving precision of the system, unless you could assign some kind of a score to the quality of tags (yes, that’s a chicken/egg thing).
This is the first service of this kind that I’m aware of, and there are lots of applications of this kind of thing in blog search. There could be an ad-matching app in there, too. And, an intermediate step in Tagyu is matching content to other content (and then to tags). I hope Adam Kalsey keeps up the R&D effort on this. Tagyu has a super-clean looking site. Very nice.
btw, for this post’s text, Tagyu returned the following tags: tagging del.icio.us tools. Looks good to me.