But, most FP languages have only recently started gaining real traction outside academia. There are some great tools written in e.g. Haskell: pandoc (a document converter), Hakyll (a static site generator), Darcs (version management), xmonad (an X11 window manager), git-annex, and multiple web frameworks (Yesod, Snap, Happstack).
In recent years, some important foundational libraries have been developed (bytestring, text, vector, repa, conduit/enumerator, etc.). I can imagine that it's pretty much the same in OCaml and F#.
In fact I think this is the only software that I know is written in a functional language that I use on a regular basis. I've always figured that said very good things about OCaml. (Not that I've ever gotten around to learning OCaml, mind you.)