Tagging’s Long Tail

Tagging systems offer a fascinating opportunity to study how people tag and what collective wisdom can be generated from the masses. Tim Spalding, in his a recent post at Thingology, The Long Tail of Ann Coulter, observes that tag use in LibraryThing resembles the Long Tail principle. That is, a few tags are used a great deal to describe a given item, while other tags are used just once. These singleton tags reflect the idiosyncratic nature of individual taggers.
I’ve been thinking about the value of these singleton tags, without conclusive results, in connection with MTagger, the tagging application we built at the University of Michigan library. With the 8.5 million items in the library catalog, or even the 55,000 web pages on our site, will enough tags ever be applied to enough items to make it a useful mode for a newcomer to find an individual item, or are they just an aide-memoire for the person who applied them? In other words, do tags way off in the Long Tail matter?
The more I’ve pondered this, the more I realize that it’s not an either-or question. Tagging, at least in the library environment, is most valuable as a personal collection tool. It offers a way for library users to bring together things that seem similar to them for their own purposes. The real value of tagging is like that of a library: it’s the collections, the constructed universe of things that someone (a librarian, a subject expert, a user) brought together. While my tags may prove of no value to anyone else in finding a particular item, the mass of items I’ve used that idiosyncratic tag on may very well guide a future user in resource discovery.