Processing is a “programming environment for exploring the electronic arts”. It seems like an Actionscript-level software environment: focused on graphics and interaction, with event handlers written in a simple structured language. People seem to have built a lot of cool stuff with it, though the source code seems more math and array intensive than I would have thought.

For further exploration: the two creators of Processing seem to both be prolific polyglots, each with their own site full of interesting tidbits: Ben Fry and Casey Reas.