Not really survival related, but back in graduate school my friends in the low-temperature physics lab used condoms as a critical part of a vacuum regulator. I walked in there once to hear them arguing over whose turn it was to enjoy the privilege of going out to the drugstore to buy more.
Churchill is reputed in WWII of contacting a condom manufacturer to make muzzle covers for soldiers - keeps the water out of your rifle in the rain.
"PS – Buy non-lubricated & no spermicide condoms."
Heh, yeah that Condom slingshot could be very dangerous if it is so slippery!