MooTowel is a reactive extension for MooTools, designed to make event-based code easier to write and even more important: easier to read.
How to use
At the hart of towel.js is a modular helper system called towel, including two helpers called UI and FX. These helpers produce objects that can be linked together: one object detects whether the mouse button is pressed, the other one changes style attributes.
By linking these objects together a whole range of effects can be created and added to a page.
For more help and examples, go to http://www.toweljs.org/.