Nodebox!

Quartz Composer is a node-based visual programming language provided as part of the Xcode development environment in Mac OS X for processing and rendering graphical data.Quartz Composer uses OpenGL (including GLSL), OpenCL (only in Mac OS X 10.6 and later), Core Image, Core Video, JavaScript, and other technologies to build an API and a developer tool around a simple visual programming paradigm. Apple has embedded Quartz technologies deeply into the operating system. Compositions created in Quartz Composer can be played standalone in any QuickTime-aware application (although only on Mac OS X 10.4 and later), as a system Screen Saver, as an iTunes Visualizer, from inside the Quartz Composer application, or can be embedded into a Cocoa or Carbon application via supplied user interface widgets. Because Quartz Composer makes extensive use of hardware acceleration and pixel shaders, it is recommended to have a graphics card with at least 32 MB of VRAM. While Quartz Composer is included with the iPhone SDK, there is currently no way of running Quartz Compositions on iOS devices. »

Fugio (pronounced foo-gee-oh) is an open visual programming system for building digital art and creative projects quickly, with no programming experience required.

Vuo lets media creators make interactive animations, exhibits, performances, and professional-grade media projects by connecting up simple building blocks. Media creators can use these blocks to manipulate audio input, images, layers, videos, and 2D + 3D graphics, as well as record high-quality video of the results.

PatterNodes is a tool for creating graphical patterns, gradients or illustrations based on repetitions. This is done by defining a sequence of steps, a recipe or sorts, that describes the pattern. Each pattern element or operation is represented by a little panel called a node, and the nodes are then linked by connections drawn between them. As the nodes can be freely combined and connected this gives you a very flexible and powerful interface.

vvvv is a graphical programming environment for easy prototyping and development. It is designed to facilitate the handling of large media environments with physical interfaces, real-time motion graphics, audio and video that can interact with many users simultaneously.

Fragmentarium is an open source, cross-platform IDE for exploring pixel based graphics on the GPU.

Context Free is a program that generates images from written instructions called a grammar. The program follows the instructions in a few seconds to create images that can contain millions of shapes.

Protovis composes custom views of data with simple marks such as bars and dots. Unlike low-level graphics libraries that quickly become tedious for visualization, Protovis defines marks through dynamic properties that encode data, allowing inheritance, scales and layouts to simplify construction.Protovis is free and open-source, provided under the BSD License. It uses JavaScript and SVG for web-native visualizations; no plugin required (though you will need a modern web browser)! Although programming experience is helpful, Protovis is mostly declarative and designed to be learned by example. »

Shoebot is a pure Python graphics robot: It takes a Python script as input, which describes a drawing process, and outputs a graphic in a common open standard format (SVG, PDF, PostScript, or PNG). It has a simple text editor GUI, and scripts can describe their own GUIs for controlling variables interactively. Being pure Python, it can also be used as a Python module, a plugin for Python-scriptable tools such as Inkscape, and run from the command line. It was directly inspired by DrawBot and Shoes. Thus, “Shoebot.” »

Fugu is a procedural modelling system for 3D graphics. It supports the generation, manipulation and animation of 3D form using scripts written in the Lua programming language. Fugu contains a code editor with all the usual bells and whistles, and a 3D view in which to visualise your design.

Prismacode is an easy programming language for creating 2D geometric graphics. It's a combination of logic and art -- there are no right or wrong answers.

Evaldraw allows you quickly write small programs in its C-like language. It supports static variables, enums, arrays, functions and just recently structs.