Resources

Processing.org
processing.org
Home page for Processing.
Processing Reference
Main reference for Processing language, can be ordered by category and alphabetically. Your constant companion.
Processing Tutorials
A collection of tutorials for Processing, some on the basics and some on more advanced topics.
Processing Libraries
Libraries are extensions to Processing. Some are built-in, some are contributed. They are listed here. Usually, when a library is listed, it has followed Processing standards of documentation and sample code.
Processing Forums
Discussion of Processing by the user community. A good place to look for answers. If you can't find an answer to your question, a good place to post a question.
Processing Wiki
More information on Processing, particularly on developing libraries and tools, issues on different platforms, code snippets, etc. The Wiki is not as up-to-date as other resources, but it is still useful.
Processing Javadocs
For the hardcore programmer (and the beginner looking beyond the reference), documentation of the full Processing codebase, some of it incomplete. The core documentation is likely to be the most useful.
Processing in Eclipse
There are (IMHO) great advantages to programming in Eclipse: Code is compiled as you write. You get pop-up assistance on documented classes. Classes are also completely independent of the "main" PApplet. Okay, so the interface is busy—but the benefits far outweigh the nuisances.
Resources for Learning Processing
Open Processing
A large online community of Processing users sharing code, both in Applet and in Processing.js format. Includes a web-based editor for writing Processing.js code online. You can often find library demos here.
Daniel Shiffman: The Nature of Code
Daniel Shiffamn, an earlier and prolific contributor to Processing, has generously made his course notes available. They are becoming a book.
sketchPatch
With a web-based editor for Processing.js coding, sketchPatch is a playground for sharing processing code, similar to Open Processing. Does not include uploaded applets and libraries, unlike Open Processing, so the code is generally simpler.
Processing Monsters
"Monsters" created with Processing. Silly, funny stuff, with free code.
Processing on Flickr
Images and videos made with Processing, sometimes with comments on techniques and libraries.
Java Resources
Java Platform, Standard Edition 6, API Specification (Javadocs)
If you need to dig deeper into the behavior of a particular Java class, here's the place to start. It documents the entire Java Application Programming Interface (API).
Java Tutorials
The original Java tutorials, in their current iteration.
Processing and JavaScript
Processing JS
Reference pages for the port of Processing to JavaScript.
JavaScript at Mozilla
Primary reference for JavaScript as implemented for the Mozilla (Firefox) browser.
JQuery
Processing JS is built on JQuery. Here are the home pages for JQuery.
Browser Support
Information on which browsers support various technologies, such as JavaScript.
W3Schools Tutorials
Some brief but useful tutorials on various web techniques, including JavaScript and JQuery.
Not Processing, but Cool Algorithmic Code Sites
Design Blocks
An MIT Media Lab project in visual interactive programming.
Context Free Art
A free programming language that uses "design grammars" to create images. "Context Free lets you write a set of rules about how to generate an image, and then follows those rules to create a image. The rules define each shape to be made up of other shapes"
History of Mathematics, Algorithms
History of Algorithms
From the Alpen-Adria Universität in Austria, a nice timeline of the history of algorithms through the ages in different cultures.