F# is a very cool functional programming language for the .NET platform. It's based on the ML-cariant OCaml but its creator, Don Syme, would like to think of it more as "Python for .NET." Even though Python and F# have large syntactic differences, they are similar in their static typing and ability to express solutions functionally. Since Visual Studio 2010, F# is now a first class citizen of the .NET Framework and is also available to OSX/Linux platforms via Mono. F# is currently in production use at many algorithmic trading companies and other scientific arena. It can also be used in Web Development (google WebSharper) or see ASP.NET MVC 3/4 F# Project Templates. F# is also used in Game Development (The Halo 3 True Skill ranking was implemented using F#. Try it now --> http://www.tryfs.net