SQL Injection Cheat Sheet : Samples are provided to allow reader to get basic idea of a potential SQL Injection attack and almost every section includes a brief information about...
Fat-Free Framework : A powerful yet easy-to-use PHP micro-framework designed to help you build dynamic and robust Web applications - fast!
Idiorm and Paris : A minimalist database toolkit for PHP5.
Object relational mapper (ORM), fluent SQL query builder and Active Record implementation for PHP.
Gophercises : FREE coding exercises for budding gophers
This is a collection of known design patterns and some sample code how to implement them in PHP. Every pattern has a small list of examples (most of them from Zend Framework, Symfony2 or Doctrine2 as I'm most familiar with this software).