TagCloud is an automated Folksonomy tool. Essentially, TagCloud searches any number of RSS feeds you specify, extracts keywords from the content and lists them according to prevalence within the RSS feeds.
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M. Halvey, and M. Keane. WWW '07: Proceedings of the 16th international conference on World Wide Web, page 1313--1314. New York, NY, USA, ACM Press, (2007)