CoffeeHandler is a project mainly written in C#, it's free.
CoffeeHandler is a .NET http handler for CoffeeScript.
CoffeeHandler is a .NET http handler for coffeescript-dotnet that compiles CoffeeScript to javascript.
Add the following to the httpHandlers section of your web.config:
<add path="*.coffee" verb="*" type="CoffeeHandler.CoffeeHandler" />
Note: This is only for development purposes and should not be used in a live environment. It should be a part of your builds to create js files for all coffee files.