Some time ago, Howard Rheingold asked what the members of the CooperationCommons would propose as innovations for the Delicious social bookmarking site.

My suggestion was that we should have a tool to link related tags together, as different people choose different tags to denote similar knowledge objects. So a tool that would look for tags collecting the same type of content, and the ability to group the material in such tags, listed by popularity of the tagged objects, would be very useful in overcoming the separation that tags are inducing. While the network feature in Delicious is already most useful, it is in fact my most favourite tool to keep up with developments, because it collates the collective intelligence of the smartest people that I know, the current version is too much of an aggregation, and it would be useful to create specialized subnetworks, of certain people with certain specific tags for example.

The good news is that David Weinberger reports on a very similar solution being implemented at LibraryThing:

“At LibraryThing, people list their books. And, of course, we tag ‘em up good. For example, Freakonomics has 993 unique tags (ignoring case differences), and 8,760 total tags. Now, tags are of course useful. But so are subject headings. So, Tim has come up with a clever way of deriving subject headings bottom up. He’s introduced “tagmashes,” which are (in essence) searches on two or more tags. So, you could ask to see all the books tagged “france” and “wwii.” But the fact that you’re asking for that particular conjunction of tags indicates that those tags go together, at least in your mind and at least at this moment. Library turns that tagmash into a page with a persistent URL. The page presents a de-duped list of the results, ordered by interestinginess, and with other tagmashes suggested, all based on the magic of statistics. Over time, a large, relatively flat set of subject headings may emerge, which, subject to further analysis, could get clumpier and clumpier with meaning.”