* http://fable.io, which is a modern F# to JavaScript compiler that lets you build Elm-style apps, access React and all that fun
* http://ionide.io which is an F# integration for Atom and VS Code that is doing amazing work towards bringing F# to a fully cross-platform ecosystem
* http://notebooks.azure.com which is (very new) free Microsoft-hosted Jupyter Notebook service that provides support for the usual suspects (R and Python), but also ships with great F# support out-of-the-box
In other words, I think the language is way ahead of the libraries and tooling - there is so much more that can be done (and is being done) using F# as-is!