The Visual Display of Quantative Information, Envisioning Information, Visual Explanations, and Beautiful Evidence (I picked up all four books by Edward Tufte at his one day training course. At the 2011 SVG Open, I was blown away by Mike Bostock's D3 demo, and Niel Fraser told me to read all of Tuftes books to see where these revolutionary ways of displaying information came from)
ESV Bible, actually hoping to find time to get my Python script running so I can download the audio, chapter by chapter, because the audio version I bought is nigh impossible to navigate.