There are a few companies out there that use it as their primary language such as Tsuru Capital and my company, Alpha Heavy Industries. By definition companies using it as their primary language will be smaller companies. Standard Chartered has a very large Haskell group.
Highlighting companies which use Haskell as primary language will be beneficial to both the language and the companies. Brings along a trust factor that real money can be made while using on Haskell.
The major problem with the 'smaller languages' is that sometimes, even if you want to, and can use it effectively, it's difficult to interface with other systems.
For example, services using SOAP. Drivers to DBs and other systems.
Sometimes it's easier to have your core login in Haskell for example, then make it interface with something else in Java/C#/etc which will have plugins for everything.
I found this with OCaml too, so I decided to do something about it: http://gaiustech.github.com/ociml/