Other websites
PHP Freaks Code Library with code examples by category
PHP Freaks Tutorials by category
PHP Freaks Reference with examples for listed functions
w3 Schools Tutorial with functions by category. Good examples, but adverts on the pages
Pixelcode PHP section/a> with tutorials
PHP resource index/a> with hundreds of free scripts and examples/tutorials
Try phpBB, if you want to put a foum/bulletin board on your site. Its free, quite easy to install if you have PHP/MySQL and has quite an active community of people who maintain it.
Next article: Applications (some worked examples)