Ulises Ali Mejias at i d e a n t has written an interesting piece about the use of tags, including some guidelines as to how they might be used most effectively:
Part of the allure of classifying things by assigning tags to them is that the user can give free reign to sloppiness. There is no authority —human or computational— passing judgment on the appropriateness or validity of tags, because tags have to make sense first and foremost to the individual who assigns and uses them. And yet, the whole point of distributed classification systems (DCSs) such as del.icio.us and flickr is that the aggregation of inherently private goods (tags and what they describe) has public value: When people use the same tag to point to different resources they are organizing knowledge in a manner, commonly referred to as a folksonomy, that makes sense to them and to others like them. In other words, the tag is the object that brings a resource and a social group together via the shared meaning of a word (although tags also serve to form connections between words and new meanings, as for example when you encounter a link to the Center for Alternative Technology when looking at the tag ‘cat’).
We can say, then, that DCSs function at the intersection of individual choices and the shared linguistic/semantic norms of a social group (the folks in folksonomy). In this paper, I explore two aspects of this intersection. In the first part, I examine some of the open affordances of DCSs in terms of the agency of the code (the program; the computer instructions that make things happen). In other words, I look at how DCSs frame social activity in the process of aggregating individual tagging choices into collective information; in short, how the code shapes social action. At the same time, I also explore the implications of relegating the organization of some social functions to the code.
(Via incorporated subversion.)