TraceKit : Not all browsers support stack traces on error objects, but TraceKit squeezes out as much useful information as possible and normalizes it.
enquire.js : A lightweight, pure JavaScript library for responding to CSS media queries.
script.aculo.us : script.aculo.us provides you with
easy-to-use, cross-browser user
interface JavaScript libraries to make
your web sites and web applications fly.
D3.js : D3.js is a JavaScript library for manipulating documents based on data. D3 helps you bring data to life using HTML, SVG and CSS. D3’s emphasis on web ...
hunt : Library to detect when DOM elements become visible and disappear on scroll.
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!