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
Give your JS App some Backbone with Models, Views, Collections, and Events
Select2 is a jQuery based replacement for select boxes. It supports searching, remote data sets, and infinite scrolling of results.
Realtime application framework for Node.JS, with HTML5 WebSockets and cross-browser fallbacks support.
Ajax.org Cloud9 Editor
Advanced HTML5 Mobile App Framework. A beautiful front-end framework for developing hybrid mobile apps in HTML5. Best friends with AngularJS.
Universal video embed.
A package manager for the web, created at Twitter