Although not quite in the same vein as volunteer passengers/good luck charms:
As a 14 year-old I remember reading "The History of the Red Air Force" (origins forgotten) where it was stated that Tupolev bombers carried paratroops (sans Parachutes) holding on to cables bolted to the wings for the invasion of Finland. When flying "quite low" the troops were signalled to let go and slide off the wings into (an expected) 15ft of snow.
Even as a 14 year-old I wondered how they carried their guns...
From memory, the book didn't state how successful that strategy was or how many repeated raids were carried out.