Use it to fix old instruments.
Use it as a dog/cat/rabbit/frog/lizard/etc. leash.
Hold on toupees.
Duct tape annoying, rambunctious students to their seats.
Reupholster the roof on a '83 Mustang convertible (or any vehicle for that matter).
Attach it to the end of a yard stick (sticky side out) as a way to get pennies out from behind the couch.
Surgical bandage.
Fix a cigarette that is broken at the filter.
A clothesline when you're out in the middle of nowhere. (Peace Corps favorite.)
Use it as a substitute for Bondo.