Amongst the big picture changes in Internet Explorer 9, there's also quite a few less obvious improvements. One neat feature for keyboard shortcut junkies? The ability to cut and paste tabs between different IE windows.
Just use Control-M to 'cut' a tab from one IE window, and Control-Shift-M to paste it into the other. As a keyboard shortcut junkie, you'll already be using Alt-Tab to switch between the windows. It's not a crucial feature, but it's a handy option for multiple tab junkies, and in an era where keyboard shortcuts are often ignored, it's good to see some new choices.