Vanilla List : The Vanilla Javascript Repository. A searchable repository of dependency-free JavaScript libraries. Over 100 projects and growing.
meSpeak.js : meSpeak.js (modulary enhanced speak.js) is a 100% client-side JavaScript text-to-speech library
InstantClick : InstantClick is a JavaScript library that dramatically speeds up your website, making navigation effectively instant in most cases.
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 ...
Zepto.js : Zepto is a minimalist JavaScript library for modern browsers with a largely jQuery-compatible API. If you use jQuery, you already know how to use Zept...
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.