Todos

http://jsfiddle.net/

http://jsbin.com/

http://codepen.io/

http://jsdo.it/

http://liveweave.com/

http://tinkerbin.heroku.com/

atuação

http://jsperf.com/

SVG (D3)

http://livecoding.io/

http://tributary.io/

http://phrogz.net/JS/d3-playground/

Tela de pintura

http://livecoder.net/

CSS

http://dabblet.com/

http://cssdeck.com/