I am currently organizing my literature on tagging. When I started with research on that topic about a year ago, you could count the number of substantial contributions on one hand. Over the current year, however, the number of papers on this topic has sky-rocketed, which makes the whole area hard to oversee at the moment.
I will start with an overview of my subjective must-reads for now (all linked to citeulike):
Position Paper, Tagging, Taxonomy, Flickr, Article, ToRead Marlow C, Naaman M, Boyd D, Davis M Produced for the WWW06 workshop, this paper was an essential contribution to characterizing different tagging systems and the resulting tagging dynamics.
The Structure of Collaborative Tagging Systems Golder S, Huberman BA A seminal reference paper introducing tagging in the scientific community. The most notable contribution are the insights the authors provide into the emergence of stable patterns in tag proportions over time.
Folksonomies: Tidying up Tags? Guy M, Tonkin E A discussion of principle shortcomings of tagging and possible resolutions.
The vocabulary problem in human-system communication Furnas GW, Landauer TK, Gomez LM, Dumais ST Although not directly applicable to tagging, this paper from the late 80s is the baseline for experiments with free-form naming and annotation in the digital realm.
Magic Words: How Language Augments Human Computation Clark A A great discussion of words as cognitive tools from a cognitive science and philosophy perspective.
Collaborative Tagging and Semiotic Dynamics Cattuto C, Loreto V, Pietronero L An inspiring discussion of the temporal dynamics of tagging systems. The core contribution is a very simple probabilistic model based on Yule-Simon memory model. Although many questions remain open, this model has some direct consequences on dealing with tags in user interfaces, which I will elaborate on in a later post.