ExpressJS - Sinatra inspired web development framework for node.js -- insanely fast, flexible, and simple
CanJS - CanJS is a JavaScript library that makes developing complex applications simple and fast.
Famous Engine - The Famous Engine is a free and open source JavaScript rendering engine.
AngularJS - AngularJS lets you extend HTML vocabulary for your application. The resulting environment is extraordinarily expressive, readable, and quick to develop.
Chart.js - Easy, object oriented client side graphs for designers and developers.
ember.js - A JavaScript framework for creating ambitious web apps