Componentjs
ComponentJS -- Powerful run-time Component System for structuring HTML5-based Rich Clients
Rest
RESTful HTTP client for JavaScript
Sproutcore
JavaScript Application Framework - JS library only
Prime
an OOP javascript library for node.js and the browsers
Queen
A platform for running scripts on many browsers
Kefir
A Reactive Programming library for JavaScript
Optics
Profunctor implementation of Lenses, Prisms, Traversals, Isos, etc.
Stapes
a (really) tiny Javascript MVC microframework
Functional Js
A functional js library that facilitates currying and point-free / tacit programming
Tweet
put twitter on your website with tweet, an unobtrusive javascript plugin for jquery
Backbone Nested
A plugin to make Backbone.js keep track of nested attributes.
Nunjucks
A jinja2-inspired templating system for javascript
Flow Js
Javascript Library for Multi-step Asynchronous Logic
Straw
Realtime processing framework for Node.js
Hydra.js
Create a scalable, maintainable and module oriented system using Hydra.js
Black Hole.js
Renders black hole gravitational lensing effects in an image canvas using WebGL, glfx.js, and numeric.js
Humane.js
A simple, modern, browser notification system