With the increasing availability, and reducing price, of personal drones - even those with cameras - it seems natural to marry this with personal safety. There is a kickstarter project to develope a drone that can track and follow a person (presumably the owner). However, the current drone structure, with multiple spinning blades, is not conducive to safety. If, however, a drone could be developed using something like the Dyson bladeless fan system, and combined with the tracking and monitoring systems being developed, we could have personal security halos that hovered a short distance above our heads and monitored our surroundings. The video could be transmitted wirelessly to a personal computer, or a cloud account, for archiving.
This idea is still some time away, however, a simpler piece of tech to start out with might be a headband, hat, or even a belt of similar functionality.