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...
E. Raad, R. Chbeir, and A. Dipanda. Proceedings of the 2010 13th International Conference on Network-Based Information Systems, page 297--304. Washington, DC, USA, IEEE Computer Society, (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)
J. Yang, and J. Leskovec. Proceedings of the Sixth ACM International Conference on Web Search and Data Mining, page 587--596. New York, NY, USA, ACM, (2013)