An interesting idea: a proposal for meta tags to reduce hits in search engines for certian search terms. Search Day gave a good example:

Let’s say you are a botanist, and have created the world’s best site about asparagus. To your dismay, search engines are swamping your site with traffic from teeny boppers who have zero interest in your beloved vegetable. Why?

Because one of the most common queries is Britney Spears. Using Carroll’s proposal, it would be a simple matter to emphasize “asparagus spears” and reduce to zero “Britney Spears” as your preferred keywords. It’s almost like applying the Boolean NOT operator to a web page, rather than to a query.