I had to recreate a terminal server user’s profile recently and they asked me if I could put the “show desktop” shortcut next to their start button.  Usually the icon is there by default as long as the quick launch toolbar is showing.  It was turned on, but the icon wasn’t there. 

I searched for a way to put it back in the quick launch, but I couldn’t come up with anything quick.  I found that you can recreate the icon yourself using notepad.

Open notepad and type the following: [more]

[Shell]
Command=2
IconFile=explorer.exe,3
[Taskbar]
Command=ToggleDesktop

Save the file as Show Desktop.scf to a location such as their documents folder.  Drag the file down to the quick launch toolbar, and it works.