Thanks to Marvilla for posting in Hardware Geeks*

Y'z ToolBar is an enhancement software which allows the user to change the toolbar icons in Explorer and Internet Explorer. The user can also create and add their own themes.

This software is free.

The main features

Change the toolbar icons in Explorer and IE.
It can use 17x17 pixels to 64x64 pixels as the icon image sizes for the toobar themes.
Use either bmp and png for the icon image files to create the toolbars. Using the png file format allows for alpha blending, the user has the ability to create smooth icon toolbar images with drop shadows and without jaggy edges.
It does not rewrite any Windows system files.
Access Y'z ToolBar by right-clicking the toolbar in Explorer or IE and choosing it from the toolbar customizing pop-up menu.
Makes it possible to hide the Windows flag (throbber)in Explorer or in IE's toolbar.
Available in different languages (Japanese and English).

http://www.h5.dion.ne.jp/~yzathome/s.../index_en.html