DockFun! is a simple, smart utility which lets you have an infinite number configurations of your dock, so you can organize all your applications in tidy & cool sets – version 4.0 Beta2 is now available. Then you’ll choose which dock you want turned on with a single click. For example, you can have a dock of internet applications on the left part of the screen to create more room for the browser window or you can have a dock with huge icons and great zoom effect for show how Mac OS X rocks. DockFun! is also a great tool for enabling all the hidden preferences of the dock, such as placing the dock at the top of the screen.
More info, screenshots, and download link here.