F# is often ideal for the sever-side of game and app development. See the Web Programming section for details of some server-side technologies. For example, F# is used on the server-sid of one of the largest Facebook social games, as described in this interview.
There are some higher-level app development stacks of particular interest to F# users:
MonoGame is an Open Source implementation of the Microsoft XNA 4 Framework. The goal of the project is to allow XNA developers on Xbox 360, Windows & Windows Phone to port their games to the iOS, Android, Mac OS X, Linux, Windows 8 Metro, and PlayStation Mobile.
Microsoft XNA is a set of tools with a managed runtime environment provided by Microsoft that facilitates video game development and management. XNA attempts to free game developers from writing repetitive boilerplate code and to bring different aspects of game production into a single system.