The PHP Function Index (PHPfi) is a simple browser to quickly look up any PHP function. Its search offers realtime-filtering of the function list and its AppleScript interface lets you look up functions easily from within your favorite editor (like BBEdit or any other scriptable app).
To be as up-to-date as possible PHPfi uses the original documentation from php.net, parsing it, and displaying it in an intuitive and clearly arranged interface. It uses an offline version of the manual for optimum speed.
PHPfi is free for academic and hobbyist users, but from professionals who earn their money with PHP coding I ask a small registration fee.