I mentioned in the other thread that I had used a piece of tube as an emergency shim to keep a seat post from sinking down into the seat tube. They can also be used as permanent shims on mountings that go around the handlebars or tubes for lights, computers, locks and so forth. (Pieces from an aluminum beer can can also serve as shims.)

You can also hold up your pants with rubber cut from inner tubes. Just put it behind two adjacent belt loops and cinch knot it. This is known as a "jailhouse belt" or it's sometimes called (where I work) a "psych ward belt."