From Vitas Enterprises:
Taskbar Organizer enables you to rearrange the program entries on your Windows taskbar to your liking instead of the Windows default arrangement. When you open a program, Windows adds an entry to the end of the taskbar, which is sometimes inconvenient. Now you can reorder the tabs on the taskbar anytime you like, keeping similar programs together or moving your favorite program next to the Start button. This program doesn't affect the QuickLaunch buttons in any way and rearranges only the open windows portion of the taskbar.