I'd love to find a way to have it compile in real time
to another window. But the closest I've seen is the CoffeeScript build command that will save a .js... if you have that open in another window you can tab back and forth after each save/build. But that's not good enough for me.
What I really like is what the CoffeeScript website has where you can edit and see real time compilation. So, using that as a basis, I wrote up a full screen version of that that also includes syntax highlighting. You can see it working here:http://w.illia.ms/coffeescript-scratchpad/
Please keep in mind that this is far
from professional. I got fed up one afternoon while using the little editor on CoffeeScript's website and decided to do something a tiny bit better. Using the CodeMirror library for an editor I was able to add syntax highlighting and make it "full screen." It could probably be improved a ton, so feel free to download my code and make it better. I have it in a public repo here:https://bitbucket.org/seanwcom/coffeescript-scratchpad