PHP-O-Lait is a library that, in 2 boiler-plate lines of code, allows you to call server-side PHP code from client-side JavaScript. It's so easy, in fact, that you don't need to know how it does it (hint, it uses Ajax and JSON).
JPSPAN provides tools to "hook up" PHP and Javascript, for the purpose of fetching data from PHP into a web page which has already loaded, without reloading the entire page. It allows you to call remote PHP objects as local Javascript objects
A javascript library for remote scripting. sizax allow to call functions and objects methods without performing a browser refresh. The return value can be given to callback function, evaluated as javascript or replace the content of a html element.