TraceKit : Not all browsers support stack traces on error objects, but TraceKit squeezes out as much useful information as possible and normalizes it.
Modest Maps | Home : Modest Maps is a small, extensible, and free library for designers and developers who want to use interactive maps in their own projects.
voxel.css : The goal of this project is to provide a lightweight 3D CSS library with very simple implementation.
PeerJS : Peer-to-peer data in the web browser.
PeerJS completes WebRTC as an API abstraction, connection broker, and binary serialization format
xui.js : A super micro tiny DOM library for authoring HTML5 mobile web applications.
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.