Travis CI is a free continuous integration service that you can use to test your open source projects. It works best in conjunction with commit notification hooks from GitHub so it kicks off a new build on each push to your repo. Status is reported on the Travis CI site and email is sent to tell you about updates to the current build status (e.g. it has started failing).
There is documentation on the Travis CI site about how to run Travis for Node.js applications. But not explicitly how to do it with CoffeeScript on Node.js. I wrote up a blog article to show you exactly that.