ExpressJS - Sinatra inspired web development framework for node.js -- insanely fast, flexible, and simple
Pixi.js - Fast lightweight 2D library that works across all devices
Famous Engine - The Famous Engine is a free and open source JavaScript rendering engine.
Snap.svg - Snap.svg is a javascript SVG library for the modern web.
Chart.js - Easy, object oriented client side graphs for designers and developers.
Raphael - Raphael.js is an Object Oriented drawing library. It is good at making in-depth diagrams with complex interactions.