So I thought I'd try and turn this into a "Show pics of the interesting stuff you use bicycle inner tubes for" thread
. Here are some contributions-
The throttle grips on my bikes are completely round, and although they have rubber wraps, being round they are difficult to keep a grip on with thick gloves, or over any long rides. There are aftermarket grips with horizontal ridges, but they're expensive, I'm cheap, and I live by the philosophy "why buy it if I can make it". So I cut a section of scrap aluminum tubing, riveted some thick leather strips across it, and secure it to the throttle using several 1" wide sections of inner tube. The tube not only holds the "grip enhancement" in place, but being rubber, they are also grippy themselves. Got one on each bike, and they've been serving me well for over a decade (have to change the bands from time to time)
First pic with the inner tubing, second without, third a pic of just the "enhancement".
The other pic is a 27mm wrench that I always carry when I leave home, in case I have to deal with any "loose nuts" I may encounter in my travels. The wrench measures 14" long.
As for other interesting uses, on a few occasions I've used sections of inner tube to make improvised, emergency plumbing repairs in bathrooms and kitchens while waiting for Home Depot to open. A long, stretchy, durable piece of tubing can really come in handy.