To open the Application Switcher miniwindow, drag all the way to the bottom of the Application menu, then drag beyond the menu. When the outline of a window appears, release the mouse button. The Application Switcher is now running. Click an icon in the Application Switcher miniwindow to bring that application to the foreground.
You can also use the Application Switcher to open documents by dragging a document icon onto the icon of an application in the Application Switcher miniwindow.
Application Switcher supports AppleScript to configure its appearance.
The Application Switcher can be anchored to a corner of your screen, show large or small icons, hide or show the application name, have a horizontal or vertical orientation, as well as other controls.
For a complete description of using the Application Switcher, see the Mac OS Help.