A long wish standing and soon to be granted. V20 adds this capability:
To snap to the midpoint of a line or arc, locate the element and then press M.
To snap to the endpoint of a line, arc, or curve, move the cursor to the end of the element you want to select and press E.
To snap to the center point of a circle or arc, locate the element and then press C.
To snap to a theoretical intersection point of lines, circles, curves and arcs, locate the intersecting elements and then press I. You do not have to locate the point where the elements intersect. If there is more than one
eligible intersection point, then QuickPick opens automatically to let you choose the one you want to snap to.