Free, open source D3, InfoViz, Processing.js, and Recline.js bring dynamic, interactive -- and jaw-dropping -- data-driven graphics to the Web browser
Second, while Processing.js can be used to draw graphs and charts, it's also a respectable, general-purpose graphics and animation package. Processing (and therefore, Processing.js) goes beyond data visualization, providing both 2D and 3D graphics commands, and permitting the creation of animations, interactive digital artwork, and even video games. On the Processing.js Exhibition page, you'll find links to animations of sea creatures, asteroids-like video games, sketch applications, and more.
To develop Process.js applications, you'll want to download and use the Processing IDE. (Versions are available for Windows, Linux, and Mac.) The IDE is basically an editor with Run and Stop buttons to display your Processing application in a pop-up window. The IDE also lets you export your application into a stand-alone executable. Best of all, if you're new to Processing, the download includes the source code for numerous example applications.
The Processing IDE (executing in the Java JVM) includes numerous demonstration applications. Here the IDE is shown running a simulation of planets (complete with cloud textures) orbiting the sun.