Only one stands out in my mind as truly exceptional: Advanced PHP Programming. I am willing to bet this is the best book out there for novice to advanced PHP developers. It is not the best beginner book as it has some advanced topics (as the title suggests), but the material it covers is seldom mentioned in any detail in other books.

He talks about it as a resource for programmers looking for moving to that next level and how useful it was to him (and could be to other developers) with helpful hints and more refined methods. There's a brief look at some of the contents - session management, security, database abstraction - and his opinions on them.

The book was the single greatest investment I ever made in my PHP skills. I've recommended this book to every novice PHP developer I've ever met.