When I was studying computer science I tried to steer clear of functional languages like LISP, Haskell, APL and the like. I found them way too abstract to get the things done I had in mind. Instead, I concentrated on imperative languages like Delphi, C (in its various variants) and Perl.
Perhaps it's time to think this over. Microsoft research announced F# (pronounced: F sharp), especially for projects dealing with concurrency. Goals are high, as functional programming languages are meant to solve the "biggest challenges in the industry" (as usual, I think this is part of the hype to say that). Even if they are "in their own world", F# will run on the .net Common Language Runtime.

Reminds me of a small Perl.Net project I did several years ago: a small Perl assembly using LWP to crawl a website that was controlled by a GUI written in C#. Worked astonishingly well. Unfortunately, Perl.Net has been cancelled. Maybe ActiveState should have had it named 'P#'. (Source)