Here are some links for you:
- Collabedit, Online Code Editor http://collabedit.com/
- Stypi, a realtime editor https://www.stypi.com/ (not about coding)
- ShareJS, Live concurrent editing in your app. http://sharejs.org/ (not about coding)
- Tutti, Test Javascript on different browsers simultaneously http://tuttijs.com/ (not collaborative ?)
- Bonus: a JS console for mobile http://jsconsole.com/
Hope you’ll find something useful in there 🙂