Cairo-Dock is a unified interface to your desktop : it provides a dock, a taskbar, and many applets that can be placed either inside the dock or on your desktop, at your convenience ! It uses Cairo / OpenGL to render nice graphics with hardware acceleration, which makes it very smooth and low on CPU. It's highly customisable and comes with a lot of ready-to-use themes.
(Click on thumbs to view full size images.)
Installation is easy , select your distribution and install off respective repositories. if your distro is not listed here you can compile from the source of course. after the installation users can add items easily. cairo-dock official web provides a post installation guide which can be found here.