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...
regex101 : Free PCRE-based regular expression debugger with real time explanation, error detection and highlighting.
Its Continuous! : The tweet-sized continuous integration app for PHP development.
XSS Filter Evasion Cheat Sheet - OWASP : This article is focused on providing application security testing professionals with a guide to assist in Cross Site Scripting testing.
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).