I decided to hack together an example toolbars customize window for Bug 15144.

• The browser window doesn't use the customized toolbars. This is just the UI for the customize window.
• Most icons are from here. Others I just quickly threw together myself.
• The Save button shouldn't really be there, but you can use it to save the button list to '[profile]/toolbars.rdf'. It will be loaded again next time.
• The text/icons/both option doesn't work right.

Install Example, then go to chrome://toolchest/content/sample.xul

A modified version using mpt's layout: