On the subject of logbooks... it's also interesting as a historian reconstructing the careers of a crew through their logbooks and letters, long after the fact. I have two logbooks belonging to members of my great uncle's crew - one for the nav and one for the pilot. I'm in touch with the families of two more (bomb aimer and now, as of yesterday in fact, the rear gunner too), neither have those logbooks sadly, but I live in hope.
One veteran has said to me, that if he knew there would be so much interest in his wartime logbook 65 years later he would have been more careful in filling it out!