Innertubes (yes some people still use them) are great even after you have put enough patches on them to make them a slick tyre.
Here are a few bike related uses i found
Weather guards for headset and bb
Mud guard on fork
Replacement rubber for bike light
Spacer for handlebar mounts
Chain stay protector
Temporary fix for broken rebound damper
Hanging stuff in garage
Cores removed to replace lost dowels in bed frame
Ice Axes & Ice Screw cover
Tie plants to canes in garden
Patch leaky hose in van
Retaining Straps on Bike rack (tie downs)
Dropper Post Protection Strip
One has been blocking up a draft in my fireplace for nearly 10 years now. Big gap, about an inch wide. Inserted while flat, then a few breaths from the pump and its sealed the gaps just as well as any builder alternative.
Most of my old tubes from the last 10 years or so are gainfully employed in the pursuit of driving Mrs yunki nuts..
They are in the wardrobe, under the sink, hanging on coat hooks, draped over the bannister, under the stairs, in the boot of the car, behind the telly, on top of the bookcase, under the bed, behind the sofa, on top of the fridge, in the garden and hanging from the clothes airer..
I carefully cut out two squares, glued em together with double sided carpet tape and then cut out a nice circle big enough to go round under my crown race and wide enough to cover the lower headset cup
Hopefully keep the majority of muck and water out over the winter
They make a half decent temporary sling if you/a mate nadges an arm/collar bone etc. Also good for “towing” on a group if someone is really struggling and you need to get them home/to a coffee and cake shop pronto!
I have one stretched over the moderator on my stalking rifle to stop it ringing when It brushes on foliage. I also use them as a grip surface for o ring mounted bike lights, rubber bands, tubeless patches, helmet mounts for torches, seatclamp mud seals, chain stay protector, cover for the head on my frame pump after seeing one that was so full of crap it no longer worked.