This is the Plug-ins part of Cairo-Dock project. A set of official 
plug-ins for Cairo-Dock It provides some new functionnalities like 
controling music players or note-taking, a clock or a desktop 
switcher but also some views, dialogs and desklets skins, etc.

more informations about it, please see http://www.glx-dock.org/tt_project.php

This requires cairo-dock.