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...
CSS Reference : Learn by example: cssreference.io is a free visual guide to CSS. It features the most popular properties, and explains them with illustrated and anima...
Gophercises : FREE coding exercises for budding gophers
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).