best read i find for your money has to be Digital SLR Photography.
I never buy them but often browse through when I pass Borders. Used to check out all of them, but have recently stoped at Black&White photography and a couple of others starting with "pro" . you will laugh at my choice here, but most of amateur ones are often very superficial. I find much more info in online forums, which I read 10x more
The best one but expensive is Aperture. it does not talk about equipment at all, but concentrate on photography - very inspiring!