We have been taking this a step further - when a user makes more than one selection from the search results, which we call a coselection, then we have found that there is also an implicit mutual relevance between the two selected websites.
There are a number of things that we postulate that coselections can be used for. We aggregate (or cluster) webpages using coselections as the similarity function, and we have shown that this creates clusters of webpages which are non-ambiguous - there is no other algorithm that can do this. With these non-ambiguous clusters, we are working on all of the following:
We have recently published a paper that summarises all the experimental work so far on this project (Ashman, Antunovic, Chaprasit, Smith and Truran, see the publications page).