Tim is the creator of LibraryThing, which he views as a repository of social cataloging, which he sees as something that will be of increasing importance to libraries and which will make allow them to remain competitive.
The Social Cataloging Library
Personal Cataloging: LibraryThing's primary focus allowing users to catalog their own collections. Records can be pulled in from 690 sources throughout the world via Z39.50, although most users pull in records from Amazon. Once the record is brought in users are allowed to modify their personal record as they see fit, including adding tags and reviews.
On top of the standard pieces of cataloging data LT allows users to include shared, common knowledge about the items, such as important characters and locations from the book.
Implicit Social Cataloging: Useful information generated by pooling the knowledge of individual users without them taking an active role in the process. LT creates tagclouds, recommendations, and can guess if a user will like a particular book based off this data. This information can also be used for fun, such as the brilliant unsuggester (fans of Kant will probably not enjoy Confessions of a Shopoholic).
The most important aspect of implicit social cataloging is the collection of tagging. LT houses the largest collection of bibliographic tags. It's important to note that tags are only useful in very large numbers. Searching by tags can produce some excellent results (chick lit is a wonderful search that library catalogs are incapable of, with "love stories" and "man woman relationships" being the closest subject heading). Tags can also be combined in very useful ways. Romance fans don't care about the general term, they want to find western romance, paranormal romance, or historical romance.
William Gibson's novel Neuromancer is an excellent example. The book is the defining work of cyberpunk, and in LT it is tagged according. However, LCSH labels it as "Computer hackers--fiction" and "information super highway--fiction".
Tagging allows for subject to be revisited in ways catalogers are incapable of. "Chick Lit" didn't come into popular use until after many of the books within its cannon were published, which is likely the only time when those books would have passed through the hands of a cataloger.
Tags are not always better than authorized subject headings and the two should work together.
Navel Gazing/Self Expression/exhibitionism, voyeurism: LT users love to learn about themselves, and the service generates many personal statistics for people to explore, such as personal tag and author clouds, retrospectives of assigned ratings and reviews, and various collection statistics.
Sharing: Users routinely upload files such as author photos and cover images both for their own uses and to enhance the entire community. Users have uploading a million covers to date. LT requires users to have copyright permission to post images
LT has recently begun a book giveaway program in which anyone can give away free books, some in exchange for reviews. Many publishers also regularly contribute galley copies to the community, 100's a month, again in exchange for reviews.
Social Networking: LT actively pushes its social networking features. Besides the standard friends and forums (Librarians Who LibraryThing is the largest group, but still only 1% of the LT user base) features of many sites LT promotes ways to discover new friends, or at least interesting libraries. Each profile page prominently displays links to the collections of those users with the most whose libraries are most similar, weighted for libraries sharing particularly rare items.
LibraryThing Local maps book related sites and events input by users.
Explicit Social Cataloging: When users intentionally collaborate on cataloging. LT makes it easy for users to combine/separate different editions of the same work, in a similar way to the FRBR model. Members do this about 10,000 times a day. Most people do activities like this for themselves, but their are communities of users who do altruistic cataloging for fun.
Common Knowledge is also available for author records. User have added education backgrounds, agents, editors, places lived, and many more chunks of data to the database. All of this information is then searchable. Series information is particularly useful, "no other catalog has had more Star Wars geek knowledge put into it".
Collaborative Cataloging: A group has cataloged the library of Dr. Horrible, based on one shot from the cult film. Many libraries of famous figures have been cataloged. Users can friend the Library of John Adams and then link to the marginalia he wrote that is available via the BPL. Users spent over a year cataloging the over 7,000 books of Ernest Hemmingway. The Legacy Libraries project has been taken over by the I See Dead People's Books group, and there's a great podcast available focusing on the project.
LT has organized a number of cataloging flash mobs, to quickly catalog libraries as a charitable project.
The Open Shelves Classification project is an attempt to create a new, open, classification system without many of the problems of Dewey. However, it has proven very hard to get so many bibliophiles to agree to anything and the project is not going well, largely due to communication problems.
Altruism is what makes this all work.
Libraries are behind on social cataloging. Vendors want to sell us "features". Worldcat is clamping down on data and it is problematic that while librarians may think otherwise, patrons are not familiar with the service.
LT data is available to libraries via their LibraryThing for Libraries service, which will work with the OPACs offered by many vendors. C/WMars, NOBLE and Simmons take advantage of this service. Stats have shown that LT tags are clicked on by patrons more frequently than subject headings within OPACs using the feature.