jQuery Autocomplete
Ajax Autocomplete for jQuery allows you to easily create autocomplete/autosuggest boxes for text input fields.
Chance
Chance - Random generator helper for JavaScript
Hide Show Password
Because life's too short to waste time re-typing passwords.
Envision JS
Dynamic HTML5 visualization
Ink
An HTML5/CSS3 framework used at SAPO for fast and efficient website design and prototyping
Pixi.js
Super fast HTML 5 2D rendering engine that uses webGL with canvas fallback
jQuery JSONP
jquery jsonp plugin
W2ui
JavaScript UI library for data-driven web applications
Sea.js
A Module Loader for the Web
Flippant.js
A mini dependancy-less UI lib for flipping over DOM nodes.
Framer
Modern Prototyping Tool
jQuery QR Code
qrcode generation standalone (doesn't depend on external services)
Communist
JavaScript library for web workers.
Bower
A package manager for the web, created at Twitter
Sco.js
Javascript extensions for twitter bootstrap
Qooxdoo
A Universal JavaScript Framework
Joy.js
A Joyful 2D HTML5 Game Engine.