If I could only provide one link to the most useful PHP resource, then it will be PHP 101: PHP For the Absolute Beginner. PHP 101 is by far the best one-stop resource not only for absolute beginners, as the name implies, but also for novices and veterans of other programming languages who’re picking up PHP.
The sample projects used in this tutorial are among the most fun you’ll get on any PHP tutorials. From database usage to XML traversing, you’ll get up to speed on some of those Web 2.0 jargons 😉
Seriously though, I find PHP 101 to be a perfect example of how a Getting Started series on a programming language should be written. Do you have your own favourites?