I've seen duct tape used for just a lot of things.  I've fixed leather couch cushions with it, people have made clothing with it, and once, in the middle of winter, I used it to hold a broken mailbox post together.  We couldn't dig a new hole because the ground was frozen.  The duct tape held it up for four or five years before we finally broke down and set a new post.

Recently on Iceland Air, an unruly passenger was taped to his seat after spitting on, assaulting and screaming at other passengers.  He sat quietly because they taped his mouth as well.  I can imagine the cheers on the plane as the man was subdued.

businessinsider.com

Everyone has something noteworthy that they've done with duct tape.  What innovative use have you come up with?