The current tool bar system in KDE is a bit dated, the window is filled with lots of buttons, and reordering items isn't all that intuitive. It's not all that 'user friendly'.
The existing toolbar configuration
My suggestion
I've made a working prototype of a new click and drag solution. Essentially it's a very similar toolbar configuration scheme to that of Firefox. A lot of the code required already existed in KToolBar, it just wasn't being used. This demo only really has changed to the toolbar editing dialog. If this is accepted by kde-usability people, I'll try tidying it all up, ready to be a patch to show to the kdelibs guys.
Below is a screencast showing my prototype mockup: