Cairo DOck
VoxelShop
Cairo-Dock is a desktop interface that takes the shape of docks, desklets, panel, etc
It is designed to be light, fast and customizable, and is desktop-agnostic.
It has a powerful DBus interface, to be controlled from a terminal or another application. Features can be added by plug-ins or applets, and applets can be written in C or in any language. Most actions can be done from keyboard.