While we are at it I'd very much like to have something like what I drew on the attached picture.
An information function displaying coordinates and size of a selected object or a group of objects. Anchor point (corners or center of selection) is selected by the user.
It can be incorporated in the toolbar, the status bar, a docker or a floating window. It will be very helpful when positioning objects relative to machining coordinates origin when doing CAM preparation work.
Such functionality is implemented one way or another in many drawing programs.
'Get object extremas' works but why it must be called explicitly every time when it can be always active when at least one object is selected?
(Side note: If, eventually, David adds anchor point selection to the absolute coordinate positioning in his 'Num muve' plugin it will be invaluable.

'Num move' and 'Aligner' are the most used by me plugins and I can't imagine now working without them.)
(Side note 2: CamBam's 'Align' function actually does the absolute positioning and perhaps the coordinate info with selectable anchor points can be incorporated into it. So that the user can enter the needed values based on that info.)
On the attached picture I need to move all objects so that the upper left corner of the selected rectangle is at X/Y 0/0. Currently I have to read the rectangle lower left corner coordinates and it size, then do some calculations in my head or with a calculator to determine the coordinates of the upper left corner, and then do a move or align entering the calculated value. By selecting the upper left corner and reading its coordinates from the info window I can enter the movement value without much hassle.
And those are action every one of us does constantly while working on a project.