Visualization of graph data is incredibly challenging, particularly when it comes to extremely large, scale-free graphs and social networks. A few simple searches on the Web and you will find some mesmerizing and very cool images. Perhaps the most cited...
M. Atzmueller, and F. Mitzlaff. Lorentz Workshop on Mining Patterns and Subgroups, Lorentz Center, Leiden, The Netherlands. Awarded with the Best Discovery Award, (2010)
A. Mislove, B. Viswanath, K. Gummadi, and P. Druschel. Proceedings of the Third ACM International Conference on Web Search and Data Mining, page 251--260. New York, NY, USA, ACM, (2010)