Power users know about the magic of the proxy icon – the tiny icon that appears in the title bar of most windows. (For example, Cmd-clicking on the icon does all sorts of interesting things, depending on the app.) One reader found a novel use for the proxy icon at the top of message windows in Apple Mail.
If you open a message and drag its proxy icon to the desktop, you will create an Internet Location (.inetloc) file, which points to the message. So say you wanted to have quick access to an important email; you could create a link to it on your desktop (or in the Dock, or wherever), using the proxy icon.