ExpressJS - Sinatra inspired web development framework for node.js -- insanely fast, flexible, and simple
Famous Engine - The Famous Engine is a free and open source JavaScript rendering engine.
Chart.js - Easy, object oriented client side graphs for designers and developers.
FeathersJS - Wow your users. Build incredible real-time applications in record time.
Backbone.js - Give your JS App some Backbone with Models, Views, Collections, and Events
Serenade.js - Serenade.js is a client side framework built on the MVC pattern.