WebMatrix Supports CoffeeScript
Microsoft WebMatrix has numerous new features in version 2, including: code completion for PHP, C#, Razor; iPhone and iPad emulators for mobile web development; Less, Sass, Scss, and CoffeeScript support; Nuget Gallery support that even allows me to download Orchard Modules and Themes; node.js support; etc. I mainly use Sublime Text 2 and JetBrains WebStorm / RubyMine for casual website development, but WebMatrix is free and now feature-rich providing a nice alternative.
WebMatrix and CoffeeScript
I have done a fair amount of CoffeeScript development and am very impressed with the CoffeeScript support in WebMatrix 2. I even showed how Orchard CMS Developers can develop Orchard Websites using CoffeeScript in Visual Studio with Web Workbench! The same is true for WebMatrix now. With the new OrangeBits Compiler in the WebMatrix Extensions Gallery you now have support for Less, Sass, Scss, and CoffeeScript in your websites. Choose the Gallery ( Extensions ) on the WebMatrix Toolbar and enable the OrangeBits Compiler.
If you haven't looked at WebMatrix in awhile, I recommend taking a peek at what's new in WebMatrix 2. I think you will be pleasantly surprised at all the new features in a free editor. I use WebMatrix quite a bit for developing Orchard CMS Themes, and am currently working with Microsoft to add more features to better support Orchard Module Development. With all the new code completion and extensions you'll find WebMatrix quite capable for developing websites. You can also use WebMatrix to publish to Windows Azure Web Sites.