I found religion with How to Grill (I now shoulda been the BBQ Bible) and I've been spreading the religion ever since. I've given several copies of HtG as presents and all of them have been very well recieved. Best of all, now I don't suffer through Char-raw chicken at friends' cook-outs. Instead I get Mustard Dill glazed salmon or Pesto Grilled chicken. Believe me; spread the Word and your friends (and taste buds) will thank you.
After learning some basic techniques form HtG, I'v since picked up Sauces, Rubs and Marinades (or SR&M). Try a new recipe near every week-end. Near, because the missus wants "chicken exactly the way you made it last time". Its gonna be some time before I exhaust all the permutations and inspirations from SR&M.
I've look at BBQ Bible and BBQ USA, but I'm not sure I'm ready for the deeper mysteries. I agree with Grand Scale, they look like coffe table books. I love that -- Food Anthropology as Alton Brown would say -- an important part of understanding food, but for sheer inspiration per dollar you can't beat How to Grill and Sauces Rubs & Marinades.