While I was browsing a bit around, I did find a nice site called **JS Bin**:
folk test snippets of code, within some context, and debug the code
So you can register and create an own account with JS Bin. After that, you can upload code, run it and share it with others. One of the nice features is that you can add libraries like jQuery, Ember.js and Handlebars.
P.S. And a possible starting point for Ember.js could be this one.