Unbrako offers a product called flexloc locknuts. They are completly made of metal offering more strength than nylocs. I thought these fasteners might be useful in rigging and automation. The link above also links to some information that they have created about fasteners (fasteners facts) and a white paper on fastener fatigue.
While it isn't something that occurs everyday, misuse of fasteners has caused, or been a factor in several incidents that I know of. Modern Marvels engineering disasters shows some of these, as does the book Why Buildings Fall Down.