Determining ASP.NET Application Paths

A client recently asked me how to determine from any specific point in the virtual directory structure where the path was to a specific folder hierarchy. The short answer was Request.ApplicationPath. However, the long and more informative answer is found in this article from MSDN:
http://msdn2.microsoft.com/en-us/library/ms178116.aspx
This lists all the methods of finding out path information from both the virtual directory and file system perspective of ASP.NET