MooTools is a compact, modular, Object-Oriented JavaScript framework designed for the intermediate to advanced JavaScript developer. It allows you to write powerful, flexible, and cross-browser code with its elegant, well documented, and coherent API.

Dojo saves you time and scales with your development process, using web standards as its platform. It’s the toolkit experienced developers turn to for building high quality desktop and mobile web applications.
From simple websites to large packaged enterprise applications whether desktop or mobile, Dojo will meet your needs.

script.aculo.us provides you with
easy-to-use, cross-browser user
interface JavaScript libraries to make
your web sites and web applications fly.

CakePHP is designed to make common web-development tasks simple, and easy. By providing an all-in-one toolbox to get you started the various parts of CakePHP work well together or separately.