If you work extensively with Visual Studio IDE, you most likely have created some Macros and Add-ins to speed things up. Why not share that with others (but not your manager, otherwise they might assign you more work), you can show off your skills, etc.
Take a look at Introducing the Visual Studio SDK, here you can find out more about how you could:
Add commands, windows, and other features to the IDE.
Extend the Visual Studio editor.
Enable support for a new language.
Extend data designer functionality to external data sources.
Add your own project-type templates.
Integrate custom source control.
Customize the Visual Studio debugger or create your own.
Create and manage your team test suites.
You can use one of your favorite languages as long as your favorite language is: C#, VB, VC++ to create the extensions. I have not tested F# yet and the documentation doesn’t mention it.