PhatStudio is a Visual Studio plugin which lets you quickly navigate to any file in your project in just a few keystrokes, even for very large projects. It also includes a header flip/switch to related file feature, bound to Alt+S by default. Header flip will switch between a .cpp file and corresponding .h/.hpp file. It will also switch between other related file types, such as aspx/aspx.cs and ascx/ascx.cs.
The add-in provides fast file navigation by substring match. This feature is fairly crucial if you work in projects with lots (hundreds or thousands) of files.