In what is a sure sign that the apocalypse is nigh, a company called Baby Alert International has created the ChildMinder car seat sensor that will remind a parent when they've forgotten their kid inside their car.
Forgetting your keys, your purse, even your umbrella when you're exiting a vehicle is totally acceptable and understandable. But your child? That's just ridiculous. The $US29 system uses a sensor pad that's slipped underneath the padding on a car seat, and a fob that attaches to the driver's keys. The pad detects the child's weight, and if it's separated from the fob by more than five metres while the child is seated, an alarm sounds to remind the parent-of-the-year that they've left their little one unattended in the vehicle.
A better approach might be to also remind them that they're probably not responsible enough to have any more kids. And a three strikes rule where child services was automatically called woud be ideal. [Baby Alert International via Coolest Gadgets]