Hey WordPress developers.
#1: Free PHP open source Library at www.phpclasses.org
Both sites are free and if you’re familiar with object oriented programming, you can easily adapt these scripts for building kickass WordPress plugins.
BTW, if you’re still not on board the object oriented programming bus, check out my free series on building WordPress plugins from scratch. You’ll get plain English explanation of object oriented programming for WordPress plugin development. The first post of this series is below: