A though came to my mind just now - the method of copying text around by just selecting it to copy and using middle-click to paste it. So I wonder, why could one not apply the same for file operations in Nautilus? I would love to just select and middle click to copy files and maybe a Ctrl or Alt key could be used at the paste stage to switch to moving files instead of copying.
Anyone up to the challenge of writing this functionality? Should not be too hard.