Codepen seems to be a great update/alternative to JSFiddle. The interface is intuitive and beautifully laid out. I don't use Apple products or Webkit as primary design tools, but for those who do CodePen is a great testing tool for code.
I have to give the faavoriteapp crew a big thumbs up vote. Excellent for those of us who use Twitter to track things & people we want to bookmark for later reference. Great design, use it often.