I do UI, design, HTML, and CSS. I can code and I've done a lot of work with LAMP setups, but I don't really consider myself much of a hacker (mostly because I don't really love hacking as much as I do design, and I'm definitely not as good at it).

Understanding PHP/MySQL is nice because it allows me to communicate with hackers, but I wouldn't know where to start with anything serious like writing an API.