Gibber
Gibber is a live coding environment for the web browser, using the Gibberish.js audio engine, the CodeMirror code editor library and wrapping Three.js for 3d graphics and shader support. Version 2 of Gibber features a much more efficient audio engine, some interesting mapping abstractions and a server/database backend for publishing and browsing files and collaboratively live coding.
In order of preference, Gibber runs in Chrome, Safari, and Firefox. The current public URL for the Gibber environment is http://gibber.mat.ucsb.edu. Below is a code sample that shows off the mapping abstractions in Gibber by mapping the output envelope of various drum sounds to the rotation of a Cube and a shader uniform.
// Electronic Drum synth/sequencer
a = EDrums('x*o*x*o-')
// create a cube
b = Cube()
// map the rotation of the cube
// continuously follow the amplitude of drums
b.rotation.x = a.kick.Out
b.rotation.y = a.snare.Out
// a shader that simulates film grain and video noise
f = Film()
// map the scanline count to the hihat output
f.sCount = a.hat.Out