For a dozen years, there's been one functionality I wished that Windows would include: the ability to move taskbar buttons. For instance, I like to keep my Outlook inbox as the first button on the taskbar, so I always know where it is. But if for some reason I have to close Outlook, then the button is in the wrong place and the only way to to move it where I want it is to shut down things.*
I kept waiting for Microsoft to add this functionality -- it seems simple enough -- or for someone to create software to do it.
And, finally, I found it: Taskbar Shuffle. It's probably been around for a bit (this is version 2.5), but I finally heard about it. The program runs in the background and lets you move your buttons around as much as you like.
You can also group them on the taskbar. I don't like Microsoft's grouping function, since if you have several windows open, it's sometimes hard to keep them straight. This will group several buttons so they're right next to each other -- and do it automatically.
It also lets you move system tray icons around and shut down buttons with a click.
All in all, an excellent addition to your Windows utilities.
*You can do it with RocketDock -- it has the option to minimize windows to the Dock. I don't find that particularly useful, except for this. Turn it on, minimize the windows (except for the one you want to move), then turn it off.