Very nice article with some cool visualization graphs - do not miss the interactive versions of the images shown.
Jeffrey Heer, Michael Bostock, and Vadim Ogievetsky. 2010. A Tour through the Visualization Zoo. Queue 8, 5, Pages 20 (May 2010), 11 pages. DOI=10.1145/1794514.1805128 http://doi.acm.org/10.1145/1794514.1805128