data mining analysis of musical social networking service Last.fm
Cytoscape is an open source software platform for visualizing complex-networks and integrating these with any type of attribute data. A lot of plugins are available for various kinds of problem domains, including bioinformatics, social network analysis, and semantic web.
This started with the simple question "how exactly does package X pull in package Y when I install it". The only way I knew of was to use aptitude interactively and just guess which package was the most likely culprit.
Gephi is an interactive visualization and exploration platform for all kinds of networks and complex systems, dynamic and hierarchical graphs.
View real-time data and statistics from any logfile on any server you have SSH access to, in an intuitive and entertaining way.
