I think the most useful thing I've ever found was a piece of Dyneema cord that somebody must have dropped on the way in or out of the Scouts camp site at Spitewinter. I'd have handed it to the warden but it had been run over a few dozen times by the time I picked it up so I took it home and gave it several good washes. Seems like some of you are pretty careless with your kit, can I sell you a bit of cord, to tie it to your person?
Sometimes I need to 'find' something to get a job done and I'm not above a bit of dumpster diving to do it. A couple of years ago a customer invited me for a sail on his boat, which he keeps in the marina at Ipswich. You need to motor quite a way from the marina before getting the sails up. We were almost ready to leave the marina but he couldn't fill the tank with diesel from the cans he'd taken because he didn't have a funnel. So I dragged him around the marina looking in the bins for a discarded plastic bottle to make one. He was hugely embarrassed and kept trying to get me to stop, but I wouldn't stop until I'd found a bottle, made a funnel (that took all of 30 seconds once I'd found a suitable bottle) and handed it to him. He filled the tank no trouble, but he never asked me to sail with him again!