Don't forget [u]Zen Guitar[/u] if you're interested in mental attitude and the psych of learning guitar. It's a good one, a quick read and can be had fairly cheaply as a paperback or for Kindle. Writtin by Philip Toshio Sudo, it's a fun, easy read but full of good stuff. I, and others familiar with it, go through it at least once a year. Do a Forum search on the title and you'll find about a dozen posts about the book.

But for actual playing and learning guitar, which the above is not about, my long-time favorite is [u]Guitar Fretboard Workbook[/u] by Barrett Tagliarino.

Good luck, have fun.