I still find it suprising that even Windows Vista lacks one of the most trivial features known to mankind, yet it still manages to be bloated.
Consider how the taskbar works, and how programs are displayed in there. It is basically the same as having tabs, which is key to a multi-document interface. Now, when you have a few tabs open in a program and it starts to get a bit unorganised, what can you do in 99% of all programs? Reorder your tabs, that's what. You simply drag a tab to another spot on the tab bar and look, it's now moved there. Easy. I find this feature a must-have in order to keep things organised.
So, this makes me wonder why on earth Windows lacks this extremely basic feature. I find myself instead having to load each program in order so that I have everything where I want in the taskbar. And as I said, the taskbar is a tabbed interface.
This void is filled with Taskbar Shuffle. It does exactly that, and no more. It's extremely lightweight and can be set to start up automatically when Windows is booted. And it's free. Unfortunately, there is no version released for x64 though, and the x86 version will not work with Windows x64, so if you are running 64-bit Windows, you are still left in the dark.
Taskbar Shuffle