Give your JS App some Backbone with Models, Views, Collections, and Events
Advanced HTML5 Mobile App Framework. A beautiful front-end framework for developing hybrid mobile apps in HTML5. Best friends with AngularJS.
Select2 is a jQuery based replacement for select boxes. It supports searching, remote data sets, and infinite scrolling of results.
Ajax.org Cloud9 Editor
Universal video embed.
Realtime application framework for Node.JS, with HTML5 WebSockets and cross-browser fallbacks support.
Simple HTML5 Charts using the <canvas> tag
The official jQuery user interface library.