I’ve been pretty skeptical of tagging. There is a lot of evidence that most people don’t bother to associate keywords with content, no matter how easy the software makes it. And tags drift over time, and people disagree on the meanings of individual tags. And search engines make it easy to search the raw text of sites, so why bother with adding keywords? If I want to annotate a site with keywords, well I can just create a blog entry that uses those keywords, and I will be able to find it later on my own blog, or on Google.
But I am intrigued by Tagcloud, thanks Phil. And by the Tags Power Tool for movable type. These both make it way easier to automatically create a category hierarchy for my own site. I try to use categories today but they have all the problems of tags; these tools would perhaps help me to automatically create tags and categories.
I guess I am still skeptical about tagging schemes that require people to explicitly tag content, but tools which smartly autogenerate tags seem interesting and possibly useful.