A partial list of arts-engineering toolkits and programming environments. Learn a new one today!

Arduino – Open-source electronics prototyping platform.
ChucK – Strongly-timed, concurrent, and on-the-fly audio programming language.
Cinder – Free and open source library for professional-quality creative coding in C++.
Flash – Adobe’s standard for delivering high-impact, rich Web content.
GLSL  – A high-level C-style shading language for OpenGL.
Grasshopper – Visual programming language for generative modeling in Rhino.
Max/MSP/Jitter – A visual programming language for music and multimedia.
Maya Embedded Language (MEL) – A scripting language for the 3D graphics software, Maya.
NodeBox –  A free, cross-platform library for generating 2D animations with Python.
openFrameworks (+ ofxAddons) – An open source, cross-platform C++ toolkit for creative coding.
Processing – An electronic sketchbook for developing ideas in Java.
Processing.js – Sister project of Processing, designed for the web using Javascript.
Pure Data – A real-time graphical programming environment for audiovisual processing.
Quartz Composer – A node-based visual programming language for rendering graphics in OSX.
RhinoScript – A scripting tool for the Rhino modeler, based on Microsoft’s VBScript.
SuperCollider – A programming language for real time audio synthesis and algorithmic composition.
Unity3D – An integrated authoring tool for creating interactive 3D environments.
VVVV – A graphical programming environment for large media environments.