For my work the things "missing" from other ML-family languages are a) rock-solid bindings to commercial RDBMSs and b) an easy way to make simple GUIs. The .NET platform gives me those "for free" and F# is sufficiently close to OCaml that it's an easy transition.

Learning my way around the .NET libraries (having never been a C# programmer) is the biggest hurdle. Last time I did this sort of thing on Windows, MFC and ATL were all the rage...

I recently completed a project using FParsec (http://bitbucket.org/fparsec/main), which is a parser combinator (http://en.wikipedia.org/wiki/Parser_combinator) library based on Haskell's Parsec (http://www.haskell.org/haskellwiki/Parsec).

"WebSharper"

http://www.intellifactory.com/products/wsp/Home.aspx

---- example:

"This sample builds upon the formlet sample illustrating how formlets may be converted into flowlets for expressing sequences of web forms."

http://www.intellifactory.com/products/wsp/samples/Flowlet.a...

I hadn't heard of this, but it looks really interesting. Do you have any experiences with it you can share?

The lib I really like is the F# powerpack.