This safety light for runners never needs batteries
The jmpLite generates electricity through the motion of your body while you're running, so it will keep flashing as long as you're moving.
There have been a lot of ideas for using motion as a power source, by converting the kinetic energy of a moving object into electricity, and while many of them call for a larger-scale deployment (such as sidewalk or speed bumps or a dance floor), this latest one is probably the most fitting application of it yet.
One of the most important safety steps we can take when running, cycling, or even walking, during early mornings or after dark is to be as visible as we can, and that can be easily done by wearing reflective clothing/accessories and a light or two. There's no shortage of designs and colors of those little blinking safety lights on the market right now, but virtually every single one of them has a weak point, which is the battery.
If you want to go running after dark but the batteries in your safety light are dead, they either need to be replaced with new ones (assuming you have some spare ones handy), or recharged (if you have rechargeable batteries and time to wait). However, if you had a safety light that could use the motion of your running to generate electricity to power its bulbs, you might not ever have to think about batteries ever again (well, at least not for this).
The jmpLite, which is said to be virtually waterproof, can be worn on the waist, or strapped to an arm or leg (or head), and it begins blinking automatically with movement, so there's no worries over whether you switched it off or not, and no battery to run down.
The people behind jmpLite are seeking some crowd support and funding with a Kickstarter campaign, and the first devices are promised to backers that pledge at least $20 to the project.