The guys at the NewbieNetwork have official recommended a book, the PHP Developer's Cookbook. As he says it, this book is not a book to learn PHP with, but, definetly a book if you are going to do anything '31337' with your PHP.
Also today, I wanted to thank you guys for the growth that you've caused for this site. I know there's a lot of you that have been with us from the beginning, and some that are new - but please, keep up the support! You're making this site great with the interaction and encouragement. It's what keeps me doing this.