-1 for Understanding Exposure. Never have understood why it's so widely recommended - first book I read as a beginner, and didn't help me understand exposure one little bit. A lot of time discussing Bryan Peterson and mincing around exposure concepts, not much really explaining exposure. Histograms barely mentioned, digital cameras are treated as though they have only just come in... Do not recommend it for a digital photography beginner.
I found Ross Hoddinott's Digital Exposure Handbook the best technical guide for digital photography. John Hedgecoe's Complete Guide to Photography was fantastic for actually getting me taking photos, although not particularly about digital photography .