This is the data used to produce the results shown in the paper below.
Source: A crawl of Last.fm users, their annotations, friends and neighborhood relations, and group membership.
Date range: First half of 2009.
Schifanella, R., Barrat, A., Cattuto, C., Markines, B., and Menczer, F. (2010). Folks in Folksonomies: Social Link Prediction from Shared Metadata. Proc. 3rd ACM International Conference on Web Search and Data Mining (WSDM). arXiv Preprint