In a new post to his blog Kevin Schroeder talks about a book he's written about some of the stranger things you can do with PHP - You want to do WHAT with PHP?.

You will not find another book on the market like it. Mostly because other PHP authors are not as crazy as I am. [...] In short, if you want a book that goes beyond the practical for the purpose of expanding your mind, this is the book for you. It is not meant to be a "cookbook", pre se. It is meant to, as Einstein put it, stretch your mind so that it does not return to its original shape.

You can see the table of contents [pdf] and a sample chapter [pdf] about working with daemons. Other topics covered include networking/sockets, streams, character encoding, debugging, profiling and good development practices. You can pick up your copy on the MC Press site and have it shipped in early September 2010.