KineticJS HTML5 Canvas Framework
Appium is an open source test automation framework for use with native, hybrid and mobile web apps. It drives iOS and Android apps using the WebDriver protocol.
Ember.js: Create Ambitious Apps
A framework for creating ambitious web applications.
Derby: Realtime Applications
DerbyJS is a full-stack framework for writing modern web applications.
Lungo: HTML5 Framework
A HTML5 framework for your mobile applications for who want to design, build and share cross-device apps.
iio engine is a framework that speeds the creation and deployment of HTML5 Canvas applications.
Durandal intends to make the creation and maintenance of single-page applications easy and enjoyable.
RIOT.JS is amazing, and sooo underrated. It is the easiest way into full strength MV* apps if you come from a jQuery background and do not want to learn all the abstraction methods associated with the likes of Angular and Backbone.