How is Window's support for CoffeeScript? Does the compiler run on Windows?
What I would really like is to be able to run the compiler from code, allowing me to keep .coffee files on the server and compile/cache them into javascript when browsers request them.
Not quite what you are asking for, but I've recently started using the Chirpy VS add-in (chirpy.codeplex.com). It comiles CoffeeScript on save in VS, producing one readable and one minified js version.
It also handles .less, but I haven't used this yet.
The CoffeeScript compiler is written in CoffeeScript so you can run it wherever you have a JavaScript runtime running. So easy to compile in the browser if eval()ing the compilation result is acceptable. (There's some fancy <script type="text/coffeescript"> or some such example on the CoffeeScript project homepage)
Server-side on Windows... not sure, IronJS / JScript.NET I believe?
And if you don't want to use vs2010, there is also gedit on windows which has support for coffeescript.
As for online, what I do is I have an online coffeescript editor (http://ace.ajax.org/), and when I save a file (with extension .coffee), compile it to js in the browser and save both the original .coffee file and .js file back to the server.
What do you expect? To implement syntax highlighting, you basically need a full parsing and lexing engine, and you need to communicate with the actual editor so that it knows how to color and lay out the source code.
Nice to see CoffeeScript support in so many different environments!