How tocreate Sub docks in leopard

HI;
I was wondering how one can create sub docks in Osx leopard on a mac mini. I would like to have docks for different kinds of programs( dock for graphics, dock for word processing, etc). But I want only one dock on screen at a time and the ability to choose which dock I'm using from a menu.
Is that possible?

eggman

get dockspaces, Dock Spaces
it will allow you to have up to 10 different docks

So the apple os does not straight from the box give you the ability to do more than one dock? You need 3rd party software to do it? I notice that you have to have spaces set up to use dock spaces and I've never found a use for spaces.

eggman

You don't need to use Spaces necessarily with Dock Spaces...

It's an option, but not required. But to be honest I'd find switching docks using it too slow (I only use it to switch to a "clean" dock for screencasts).

What about Dragthing?