I was recently blogging about a conference presentation I was preparing, and, being a conscientious info pro, I was planning on tagging my blog post (and, heck, my Twitter Tweets too). And suddenly, I realized I was channeling my grad school Cataloging 101 professor: Am I going to be doing descriptive tagging or subject tagging?

Back in the days when librarians actually cataloged books, there were two approaches: You focused on describing the book (title, author, number of pages), and you focused on creating access points for others. So, for example, I could decide that my blog post should be described with phrases such as Online Information conference, London (the location), "30 Search Tips" (the title), and so on. Those all describe what my blog post is about.

Alternatively, I could focus on making sure that my blog post is found by people who would find it useful. In that case, I could tag it with the official or most commonly used acronym for the 2008 Online Information conference and the topics I’m covering (e.g., Web 2.0, customized search engines). The idea is to ensure that people who are looking for information on building a customized search engine, or on searching Web 2.0 content, or Online Information presentations, will find my blog post.

But how do I find the official tag for the conference? My first option is to go to the conference website to see if the organizers have already suggested an acronym to use. Sure enough, there was a page for bloggers, noting that "the Blog and Flickr tag for the exhibition and conference this year is OnlineInfo08." Out of curiosity, I ran a quick search in Technorati to see if this tag was, in fact, being used. Interestingly, other bloggers had already used tags such as Online Information 2008, online information, London, and onlineinfo2008, but no one had used the official tag yet. I realized that, by being one of the earliest ones to blog about the conference, I could have a hand in determining what the most common tag for the event was.

While bloggers haven’t yet totally gotten with the program, I am starting to see more applications being developed to take advantage of this volunteer cataloging of the web. And, yes, some day librarians will rule the world, and we will apply controlled vocabulary terms for all webpages and blog postings. Don’t worry—it’ll be a benign dictatorship.

Google Maps, for example, supports all sorts of user-generated content that can be overlaid on its maps, taking advantage of geotagged images, videos, websites, blog postings, social bookmarks, and other web content. While few digital cameras include a GPS receiver, photographers can easily bring along a GPS and note the coordinates for a photo or for a series of photos. Even more conveniently, both Google Earth and Microsoft Virtual Earth allow you to find a location and then attach the coordinates to an image in Picasa or Windows Live Spaces, respectively.

While geotagging may be helpful for outdoor photographers who want to remember, for example, exactly where in Yellowstone they took that great shot of the waterfall, it appears that most of the geotagging is done by people who simply want others to be able to find their photos and who are willing to go to a fair amount of trouble to create these finding aids. They’re doing descriptive tagging.

And it’s not just photographers who have become amateur catalogers. Bloggers include NSFW (not safe for work) warnings when linking to a page that might be flagged by an employer’s filter as inappropriate. Flickr even has a user-written file on how to catalog … er, tag your images so that they are useful to others. The tag CG (for computer-generated), for example, should be used for photos that have been "heavily altered" but not for photos simply filtered with Photoshop. I expect to see a hierarchical taxonomy of Flickr tags any day now.

While in a movie theater recently, I saw the future of user annotation and indexing—we can now buy a Blu-ray Disc of The Dark Knight and create our own video commentary to share with friends. As more user-generated content and commentary is added to the web, we will see a lot more amateur catalogers laboring to enhance retrieval. Go forth and index!