script.aculo.us : script.aculo.us provides you with
easy-to-use, cross-browser user
interface JavaScript libraries to make
your web sites and web applications fly.
ProseMirror : In-browser structured text editing component. A toolkit for building rich-text editors on the web.
Timeline : Beautifully crafted timelines that are easy, and intuitive to use.
hunt : Library to detect when DOM elements become visible and disappear on scroll.
Bespoke.js : Bespoke.js is a super minimal, modular presentation library for modern browsers, designed to foster a rich plugin ecosystem.
Rainbow is a code syntax highlighting library written in Javascript.
It was designed to be lightweight (1.4kb), easy to use, and extendable.
It is completely themable via CSS.