Handlebars provides the power necessary to let you build semantic templates effectively with no frustration. An extension to the Mustache templating language created by Chris Wanstrath.
Google Analytics on Steroids. A Google Analytics implementation with more power features.
Dojo saves you time and scales with your development process, using web standards as its platform. It’s the toolkit experienced developers turn to for building high quality desktop and mobile web applications.
Give your JS App some Backbone with Models, Views, Collections, and Events
Alloy is a UI metaframework that provides a consistent and simple API for building web applications across allthree levels of the browser: structure, style and behavior.
AngularJS lets you write client-side web applications as if you had a smarter browser. It lets use good old HTML (or HAML, Jade and friends!) as your template language and lets you extend HTML’s syntax to express your application’s components clearly and succinctly
History.js gracefully supports the HTML5 History/State APIs (pushState, replaceState, onPopState) in all browsers. Including continued support for data, titles, replaceState. Supports jQuery, MooTools and Prototype. For HTML5 browsers this means that you can modify the URL directly, without needing to use hashes anymore. For HTML4 browsers it will revert back to using the old onhashchange functionality.