The indispensable tool that works on everything... except ducts.
When I was in high school, my favorite teacher taught me my most important lesson: duct tape can be used to fix, mend, or build anything. The most important piece of kit I have in my radio producer's bag (after the microphone and the mini disk recorder) is duct tape. I can't even list the number of times it has saved me out in the field. I think the entire Baghdad bureau is constructed of it (although the duct tape you get in Iraq sucks).
Forbes.com recently ran a series on the 20 best tools ever. It's got the predictable ones: the knife, the abacus, the rifle... etc. But apparently once Forbes posted its favorites, critics clamored for duct tape. Among the amazing uses for duct tape they list:
"It even cures warts. In 2002, doctors at the Madigan Army Medical Center in Tacoma, Wash., treated a group of patients by having them apply small duct tape patches every day; the warts disappeared in 85 percent of those treated, making the therapy far more effective than freezing with liquid nitrogen, the standard treatment. The medical applications don't stop there. Duct tape is widely used for first aid as a sort of temporary suture. The tape effectively closes up wounds until proper treatment can be found -- although it's not fun when you have to pull the stuff off your skin. Some emergency medical technician handbooks even describe how to use duct tape to close up sucking chest wounds like gunshots."
Oddly enough they say that duct tape isn't any good for one thing... ducts. Fails all the time.