PHP 4/5: OOP, MVC, Singleton.
Frameworks: Symfony 1.x + Diem, CodeIgniter 1.x, PEAR, basic about ZendFramework
MySQL 4/5, Postgresql, SQLite
ORMs: Doctrine, Propel
JavaScript + Ajax, jQuery, Mootools, ExtJS;
Ldap, XML, 3rd party scripts & libs.
UNIX: RHEL, Ubuntu, LAMP installing and managing;