Pretty sure I've seen this requested at least once, but chiming in to add my two cents:
It would be nice to be able to move up or down render elements in the Render Elements dialog. Right now there is a sort of 'hack' by which you can delete a render element, undo (ctrl+z), and it will automatically sort that render element to the bottom of the stack. In this way, you can organize the render elements list, but of course, this is not a user friendly solution.