I would also suggest that you make sure your kids know how strangers can trick them with information they might glean from a blog or other sources. For example, someone tracking a teenage girl's blog could pick up enough information to approach her at a sports event and say something like this:
Jeannie, I'm Dave from your Dad's work at Hudson, Inc. He's at the hospital with your mom, Debbie, and your brother Joey, who was just hit by a car. He asked me to come here and give you a ride to the hospital as soon as possible because Joey may die. In case you're worried, your Dad told me to prove I'm for real by telling you this: the name of your pet gecko is Lulu. OK, let's go.Would your child be smart enough to say no and take steps to verify the claim?
A great tip is to make sure that your kids know a secret password that they must demand of any stranger to prove they really have been sent by you. If the stranger doesn't give the password, the kids should just run.