xfce4-showdesktop-plugin

This plugin is now shipped with xfce4-panel >= 4.4.0.

Written by Andre Lerche, this plugin allows you to hide and unhide unsticky windows on the current workspace with one click. You can unhide all windows with a left-click, or just unhide the last window group with a middle click.

Just add it to your panel. Clic once to get the desktop, then clic once again to return to your application. Tha's all!

xfce4-showdesktop-plugin-0.4.0.tar.gz

Is now shipped with the panel, so there is nothing more to download than the panel.