CodePen - A front end web development playground.
CodeMyUI - Handpicked code snippets you can use in your web projects
JSFiddle - Test your JavaScript, CSS, HTML or CoffeeScript online with JSFiddle code editor.
Codespace - A beautiful cross-platform code snippet manager
Liveweave - Liveweave is a HTML5, CSS3 & JavaScript playground for web designers and developers
DhiWise - DhiWise is a ProCode platform that helps you build clean, scalable, and customizable native and cross-platform apps. Focus on what matters as a programmer and let DhiWise do the rest.