I have just discovered Plunker. “Plunker is an online community for creating, collaborating on and sharing your web development ideas.

• Real-time code collaboration
• Fully-featured, customizable syntax editor
• Live previewing of code changes
• As-you-type code linting
• Forking, commenting and sharing of Plunks
• Fully open-source on GitHub under the MIT license”

If you are doing web development, you might want to have a look at it. – http://plnkr.co/