CodePen - A front end web development playground.
Snipper.ml - A simple snippet manager in the menubar
JSFiddle - Test your JavaScript, CSS, HTML or CoffeeScript online with JSFiddle code editor.
Snipline - Command-line snippet organiser for power users
Liveweave - Liveweave is a HTML5, CSS3 & JavaScript playground for web designers and developers
PasteCloud - Store pieces of text or code and share it with everyone.