The state of Florida allows you to add two contacts your driver's license information, so that in an emergency they will know who to contact. This is a result of a teenager's mom not being noitfied for five hours after her daugher was in an accident (they were trying to track her down). Now, you can electronically add two contacts to your driver's license information. This information can only be retrieved by a police officer.
Here's the link if you are interested. I know I think it's a great idea. I've always wondered how my family would find out if something were to happen to both David and I.