Researchers at the School of Engineering, University of Tokyo, have produced a series of large-scale visualizations of the Blogosphere, based on datasets mainly composed of Japanese written blogs.
The results show a herd behavior of weblogs, which present globally-sparse, but locally-dense structure. The locally-cohesive 'communities' are clearly identified by the visualization. Each community is a group of weblogs that discuss the same or similar topics.
The datasets have been gathered by crawling the WWW. The crawling was operated from randomly selected entries, then tracing back trackbacks pointing to the entry to the sources of the trackbacks, and so on, until every entry connected by trackbacks was gathered.