I have used a Jeep Grand Cherokee as a winch anchor! A friend patched a hole in the Oil Pan of his Volkswagen Bus, with a beer can, and RTV (Silicone Rubber). He never got around to getting a new oil pan. I carry an assortment of nylon cable-ties - they're handy for holding stuff together. I have heard of people carrying unlubricated condoms in their first aid kits, for waterproofing finger bandages. I also carry saline solution and an empty contact-lens case, for those who wear contacts.