Initially developed to serve as a software sketchbook and to teach fundamentals of computer programming within a visual context, Processing also has evolved into a tool for generating finished professional work. Today, there are tens of thousands of students, artists, designers, researchers, and hobbyists who use Processing for learning, prototyping, and production.
Have not downloaded it yet, but it looks fascinating. See examples of what people have done.
» Free to download and open source
» Interactive programs using 2D, 3D or PDF output
» OpenGL integration for accelerated 3D
» For GNU/Linux, Mac OS X, and Windows
» Projects run online or as double-clickable applications
» Over 100 libraries extend the software into sound, video, computer vision, and more...
» Well documented, with many books available