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
I recon we should get 101 uses betwee us?