nowjs for Node

Directly call remote functions in Javascript: NowJS creates a magic namespace 'now', accessible by server and client. Functions and variables added to now are automatically synced, in real-time. Call client functions from the server and server functions from client.

SceneJS - WebGL Scene Graph Library

SceneJS is an open source 3D engine for JavaScript which provides a JSON-based API for defining and manipulating 3D scenes on WebGL.

Cocos2D JavaScript

Cocos2d-javascript is a 2D game/graphics engine based on cocos2d-iphone but designed to run in the web browser. It uses the latest features available in HTML 5 allowing real-time rendering of 2D graphics.

NClosure

Server-side Google Closure with Node.js. A fork of node-goog (which seems dormant).