Say for instance you have an online store, offering a new product to a segment of customers. The path to the catalog item is
The highlighted section specifies the url mapping. The vanity url's (Diablo_Config.aspx and Diablo_Config.aspx?loc=test) are actually just as complicated as the actual paths (testconfig.aspx and test/testconfig.aspx), but it illustrates what's possible. The following screenshots illustrate what the "customer" sees:
The aspx page that outputs the appSettings is simply copied to the application root and /Test folder for illustrative purposes. If you're interested in aspx (not code-behind) that references app settings, see the following link.