The Dock is one of the signature features in Mac OS X and for those who think it can't be customized in appearance, they need to checkout this new application called Dock Library.
Dock Library is a free application that takes the headache out of managing styles for your Leopard dock. New skins amd themes can easily be applied to the Dock in Leopard and Snow Leopard makes it more visually attractive and adds more to the OS X eye-candy.
The interface of the application is simple and easy to use. All one needs to do is download a Dock style from LeopardDocks.com or LeopardDocks.net in zip format and then simply click 'Import' from within the application to add it to Dock Library.
Once a style is added to Dock Library, simply select it and click 'Activate' to see it live. Click here to download the app, it works on both Leopard and Snow Leopard.