Visual Studio 2012 Ultimate comes bundled with a new PowerPoint Storyboard. It includes all kinds of useful SharePoint, Windows, Web etc. shapes that you can use in any Office doc. The nature of Storyboarding with accurate, scaled graphics is that you can rapidly prototype layouts and UI elements, without the amibiguity of scribbling on a white board (messy, inaccurate), or at the other end of the spectrum, making an actual page/application mockup with real control and UI elements (slow!).
With this tool you can build a storyboard from a collection of pre-defined storyboard shapes and capture existing user interfaces. Also, you can customize the layouts of your web, client, or phone applications, and link the storyboard to a work item stored in Visual Studio Team Foundation Server 2012.
More about Storyboarding with Visual Studio 2012: