The FBI has released a simple iPhone app that can store information about your children and send it to authorities in the unlikely event they go missing. Parents fill out information about the child in the app and use it to take a photo of the child. The data is stored on your phone (not sent to the FBI or anyone else) unless there is an emergency when you can email it to appropriate parties.
When I wrote about the app on my CNET blog, a reader commented that the FBI should have provided password protection to avoid anyone seeing this data if they got hold of your phone. Another reader pointed out that you can password protect the iPhone itself. Still, I agree that a password option would have been a good idea.
The app isn't as elegantly designed as it could be. For example, you have to type in gender rather than select from male or female and you're not restricted from typing in letters in fields that should be numbers only. But I don't think any of that really matters in the long run. What's important is that you have the information you need to immediately pass on to authorities and possibly the media if the need ever arises.