Question: I am not looking for a necessarily super-robust solution with a 10-year track record, but for something that can be used in a real applications, and goes beyond just being able to run an Hello World example.

My preference is to run the compiler on the server, so I can compile Haskell code ahead of time. Of course, the solution would need to be more than just a compiler, and enable Haskell code to access the API available on the browser (DOM, XHR…).

Footnote: the projects I have seen so far don't seem to be actively maintained, or to go beyond being able to run "Hello world", or in some case even to go beyond a project description.

Answer: 
There is a more complete list here:

<http://www.haskell.org/haskellwiki/The_JavaScript_Problem>

and there is also Fay (although it is only a subset of haskell)

<https://github.com/faylang/fay>
You may find this List useful:
<https://github.com/jashkenas/coffee-script/wiki/List-of-languages-that-compile-to-JS>

From the List:

```
* UHC (Utrecht Haskell Compiler) backend converts UHC core to JavaScript, allowing the compiling of Haskell code to JS.
* YHC (York Haskell Compiler) backend, as above but with YHC core language.
* jshaskell

```

I know its not Haskell but Coffee script is expression based and rather elegant IMHO.