Workbox : JavaScript Libraries for adding offline support to web apps.
SlimerJS : A scriptable browser for Web developers
Wave.js : Audio visualizer library for javascript. Create dynamic animations that react to an audio file or audio stream.
SPF : A lightweight JS framework for fast navigation and page updates from YouTube
Microjs : Fantastic Micro-Frameworks and Micro-Libraries for Fun and Profit!
TogetherJS is a free, open source JavaScript library by Mozilla that adds collaboration features and tools to your website. By adding TogetherJS to your site, your users can help each other out on a website in real time!