I don’t read visualization books nearly as much as I wish I did, but there are a handful I keep on the shelf for a rainy day, which until recently was basically never here in California. I updated the books page to show some of my favorites.
I also added a few books in my queue that I hope to get to one day. Two are new visualization books that I heard good things about, one is an introduction to statistics (mostly for teaching reasons), and the last is a not-so-new one on design.
By the way, the statistics textbook is available for free as a PDF download.