Most of you know how to code, and so you might be turned off by the easy style of Ben Fry's Processing (http://processing.org). However, even as an advanced programmer I often turn to it to prototype visual ideas. After 10 bad ideas (discarded quickly), one comes out right--then I port to straight Java, Scala or ActionScript.

(John Resig also ported Processing to Javascript: http://processingjs.org)