Fool.js - An April Fools' Day jQuery Plugin

Fool.js is a  jQuery plugin that lets you play one or more fun practical jokes on an unsuspecting visitor, and it's crazy easy to set up.  You can find a list of pranks it can perform here.

Requirements: jQuery
Demo:  http://fooljs.com/
License: ☺ License

Animate.css - A Bunch Of Cool, Fun, And Cross-Browser Animations

Animate.css is a bunch of cool, fun, and cross-browser animations for you to use in your projects. Great for emphasis, home pages, sliders, and general just-add-water-awesomeness.

Requirements: None
Demo: http://daneden.me/animate/
License: ☺ License