Augment.js
Modern JavaScript in your IE
Straw
Realtime processing framework for Node.js
Buster
A powerful suite of automated test tools for JavaScript.
Zoom.js
zoom in on any element in the DOM
Tempo
Tempo is an easy, intuitive JavaScript rendering engine that enables you to craft data templates in pure HTML.
Parallel.js
Parallel.js is a tiny library for multi-core processing in Javascript.
Functional Js
A functional js library that facilitates currying and point-free / tacit programming
Nerdamer
a symbolic math expression evaluator for javascript
Highlighter.js
Easily navigate the DOM and highlight the elements - http://720kb.github.io/highlighter.js/
jQuery Tourbus
A jQuery tour/walkthrough plugin.
Underscore.db
Pure JavaScript database based on Underscore for Node, node-webkit and the browser
Twitterlib
Twitter JavaScript API library
Jumly
Rendering engine for UML diagrams in JavaScript
Css3 Finalize
Tired of adding prefix for each broswer when it comes to the new css3 attributes?
Jquery Waypoints
Waypoints is a small jQuery plugin that makes it easy to execute a function whenever you scroll to an element.
Twgl.js
A Tiny WebGL helper Library
Text Tailor.js
jQuery plugin, tailor made text to fill the height of the parent element or ellipse it if it doesn't fit