TANAGRA is a free DATA MINING software for academic and research purposes. It proposes several data mining methods from exploratory data analysis, statistical learning, machine learning and databases area.
Using RhNav - Rhizome Navigation I wrote a data aggregator for Technorati's API. The first result is a video which visualizes blog domains by analysing Technorati's Cosmos (the blogs which link to a particular URL). The video is a screencast of RhNav fetc