MagicDesktopSwitch... You can use MagicDesktopSwitch to set your Desktop Image to your current screen saver or to return your Desktop Image back to normal. MagicDesktopSwitch acts like a screen-saver switch for your background. MagicDesktopSwitch only stays open while you make your selection from the dialog box. Then it quits until you open it again to switch your desktop back to normal.
You may use this little app for free; however, if you have a dollar or two to donate for the software, then go here and select the payment link. Just a dollar or two is plenty more...
Version 1.1 has been updated to be able to start your screensaver background automatically at login. Just drag and drop your MagicDesktopSwitch app into the LogIn Items under your username in your "Accounts" System Preference pane. The icon has a fresh new Leopard look, and the dialog box has been simplified.
Mac OS X 10.4 or later, may not work with every version of OS X.