Here\'s the deal, I use Wro4j to handle the transpilation/\'building\' of .coffee files to .js ones.
Now I want to have a good editor plugin which supports CoffeeScript,
Besides CoffeScript-Eclipse: https://github.com/adamschmideg/coffeescript-eclipse (mentioned by BluesRockAddict), the other choices I know of are:
LiClipse: http://brainwy.github.io/liclipse/
Aptana Studio 3: http://www.aptana.com/products/studio3