Personal safety is a serious concern, as technologies like the Sanyo Eneloop bell alarm show. Its design is based off of the Sanyo Eneloop battery which is a rechargeable battery ready to use out of the box. Just pop the top on the Eneloop bell and it'll scare attackers — and alert fellow bystanders — with a piercing alarm. It'll also send a GPS signal to a specified cell phone that will, in turn, alert your position to your family and the authorities.
Sounds a lot more effective than your average danger whistle. At the moment, the Sanyo Eneloop is just a concept from Japan, but we wouldn't be surprised if an idea this good gets quickly incorporated one way or another.