A new analysis of data from del.ici.ous shows that, while the number of tags grows roughly in proportion to the growth of content, users can unwittingly provide bridges between networks of seemingly unrelated concepts.
V. Alfi, G. Parisi, und L. Pietronero. Abstract Book of the XXIII IUPAP International Conference on Statistical Physics, Genova, Italy, (9-13 July 2007)