Icons for the 'copy to...' and 'move to...' commands in the 'general' toolbar.
I use these file management commands more than any others, by far. Copying by drag-and-drop always requires two hands (control key + drag with mouse), and, in the heat of the moment, sometimes winds up as a move instead of a copy (the '+' on the cursor is very small...). Using F5 and F6 works fine, but also requires two two different types of interaction (select with mouse then press a key). Easiest for me would be 1) mouse click to select the file(s), then 2) mouse click to 'copy' or 'move'. This would also overcome the problem that dragging a file into a panel that's filled with subfolders (in 'full file list' display only) will put the file into a sub-folder in that panel; there's no empty space to drag to, so one must use 'small icons view' to avoid the problem. I know this is a feature, not a bug (I see the little folder icons opening up to accept a file, which is actually very cool), but it's also very easy to drop a file into a folder unintentionally and then need to go looking for it.