Some of my favorites that I used to recommend to my photography students are the books by Bryan Peterson called Understanding Exposure, any of the editions (he has an older one that is mostly film and a newer digital one.) They are equally awesome.
What I LOVE about those books, apart from the fab photos he shows, is that he always tells you what aperture & shutter speed he used. It's a great way to start familiarizing yourself (or to practice guessing what was used!) for various effects. If you haven't yet read those, I'd really recommed them!