Preferably an IDE. Integrated support for Subversion/Git is a big plus as we are a group of 6 people working.
Vim/Emacs is not that pop
Seems there's at least limited support for Cloud9 (IDE in the browser): http://cloud9ide.zendesk.com/entries/20559696-create-a-coffeescript-node-js-project
Here's a live compilation extension project: https://github.com/tanepiper/cloud9-livecoffee-ext
Discussion: http://groups.google.com/group/cloud9-ide/browse_thread/thread/0ae17400825d01f9?pli=1