cssQuery() : cssQuery() is a powerful cross-browser JavaScript function that enables querying of a DOM document using CSS selectors. All CSS1 and CSS2 selectors ar...
Vex : Vex is a modern dialog library which is highly configurable, easily stylable, and gets out of the way. You'll love vex because it's tiny (6kb minified...
swfobject : SWFObject 2 offers two optimized Flash Player embed methods; a markup based approach and a method that relies on JavaScript & offers a JavaScript API ...
Band.js : An interface for the Web Audio API that supports rhythms, multiple instruments, repeating sections, and complex time signatures.
Protovis : Protovis composes custom views of data with simple marks such as bars and dots. Unlike low-level graphics libraries that quickly become tedious for vi...
Rainbow is a code syntax highlighting library written in Javascript.
It was designed to be lightweight (1.4kb), easy to use, and extendable.
It is completely themable via CSS.