From our internation friends in Italy comes Latoserver.com, a web site that offers free resources on dynamic website development with php and mysql.. For those of you non-Italian speakers, here's a link to babelfish. It's also a nicely designed site too, so check it out...
Also, it may be a bit old, but it's still pretty good - there's an article that talks about PHP socket programming over on the O'Reilly Network (complete with cheesy illistrations - heh). They also have a neat article that talks about security with PHP and the real difference between running it as CGI and as a module.