Jouni pointed me to a forthcoming book on statistical graphics in R, written by Paul Murrell at the University of Auckland (New Zealand). R is the open-source version of S and by far the best all-around computer package for statistical research and practice.
Based on the webpage, the book looks like it’s going to be great. I was hoping to use it as one of the texts for my new course on statistical graphics, but now I’m thinking I’ll also include it as a recommended text in all my classes. I particularly like Figure 1.8 (the “graphical table”) which reminds me of my own work on turning tables into graphs.