I've tried a few times, and bounced off quite hard. I'd rather go with something more pragmatic like Ocaml or Scala or F#. Particularly since all of those interop rather seamlessly with the vast array of existing code that is written for either the JVM or .NET, yet still give you considerably better type systems than the default C# or Java.
I tend to use Scala and Java for my day job. I completely understand you. Though I feel that a lot of what's good in Scala is better and simpler in Haskell, or was influenced by Haskell, so even if I don't use it for my day job, I feel it has made my job easier and better. Knowing Haskell has made me a better Scala programmer.
As an example, whenever I had trouble visualizing what some functions would do in Scala -- because they used to have horrible signatures, though it's getting better -- I would simply test the equivalent functions in GHCi to get a feel of what they would do, because Haskell functions tend to be simpler than Scala's ;)
