Practical PHP Programming, an online book, is an industry-standard in the PHP community, definately a good place to point people who are starting PHP from scratch.
If you find that this online book has been useful to you and want to go further, go for the enhanced print version thats available from O'Reilly: PHP in a Nutshell. It contains all the best parts from this online version, as well as thousands of fixes from O'Reilly's team of technical editors.
Paul Hudson is a recognized expert in open source technologies. He is a professional developer and full-time journalist for Future Publishing. His articles have appeared in Internet Works, Mac Format, PC Answers, PC Format and Linux Format, one of the most prestigious linux magazines. Paul is very passionate about the free software movement, and uses Linux exclusively at work and at home.
Paul have also co-authored four books on Linux that are packed with hints and tips for Apache, MySQL, PHP and dozens of other server-side tools that all Linux admins deal with every day - a worthwhile read if you're serious about your system administration, these are:
