It's an idea so simple, you'll wish you thought of it: Designer Jaseok Han came up with the idea of the Rescue Balloon
kit, which in the event of a wilderness emergency helps direct SAR personnel to your location using—what else—a bright red balloon.
Here's some shakily-translated description:
When we meet with an accident in the forest, there is not a proper and sustainable way to inform the rescue team an exact position of where we are. Also it is very hard to find survivors because of the luxuriant treest overhead.
Rescue Balloon is a long tube type balloon, so that it can go up to the sky through the dense forest. Not depending on high technology, such as GPS system, people can easily use this device for safety reason.
Clearly, it's not a perfect solution, and I can imagine a raft of complications—especially if wind and weather pick up. Also, what if you get the balloon caught on a tree? Then you'd be wishing for a SPOT.
That said, it's cheaper and maybe even lighter than a SPOT, and with a few tweaks (mylar balloon, string with extra-tough tensile strength), it could be workable for "safety reason." At the very least, it smacks of a clever and creative imagination put to use on low-tech survival gear.
Either way, I just know that if I ever meet an accident in the forest, I sure hope that at least the trees are luxuriant.