Windows 7 "Show Desktop" button

"You can pin the Show Desktop to Taskbar fairly easily. Alternatively, you can add the Quick Launch Bar to the Taskbar. With the Quick Launch Bar, there will be a ""show desktop"" button visible again just like in Vista:

To get the Quick Launch Bar:

right-click on an open area of the taskbar, and choose Toolbars \ New Toolbar from the menu. You should probably also unlock the taskbar at this point.
Now paste this into the location bar of the new window: %appdata%\Microsoft\Internet Explorer\Quick Launch as shown here:

You’ll immediately notice the Quick Launch toolbar on the taskbar, but it’s all the way over on the right, so you’ll want to click on the dotted lines and then drag the toolbar all the way to the left:

it’s over on the left… but now you’ll want to adjust the regular taskbar toolbar to be closer to the left, so use the dotted lines to drag it over as well:

The normal Quick Launch that we’re used to doesn’t have text, so right-click on the dotted lines and uncheck Show Text as well as “Show Title” from the menu:

Once you’re sure it’s the way you want it, you should check the Lock the taskbar again.

courtesy of the How-To Geek."

a ready to use xp/vista button is at Softpedia