jsmad : jsmad is a pure javascript MP3 decoder, based on libmad, with an ID3 decoder written from scratch.
hunt : Library to detect when DOM elements become visible and disappear on scroll.
loglevel : Minimal lightweight logging for JavaScript, adding reliable log level methods to wrap any available console.log methods
RequireJS : RequireJS is a JavaScript file and module loader. It is optimized for in-browser use, but it can be used in other JavaScript environments, like Rhino ...
Prototype : Easy Ajax and DOM manipulation for dynamic web applications
Modest Maps is a small, extensible, and free library for designers and developers who want to use interactive maps in their own projects.