Semant-O-Matic—an experimental blog search engine. This is an impressive technology demonstration. The engine indexes eleven weblogs over the period of four months (March to June 2002) using a technique called “latent semantic indexing” or LSI. A full explanation is provided on the site but this basically means that you can type in a term such as “hobbit” and recieve a bunch of results about related topics (i.e Lord of the Rings) that don’t necessarily have to mention the word itself.
I’ve been doing some reading on the semantic web recently and it looks like the way things are headed—Semant-O-Matic provides an easily understood demonstration of why topics like metadata are becoming so important.