When I was pregnant with DS someone suggested this to me, and I thought it was a good idea:
Print out and tape to the side of your infant carrier/ carseat a list of emergency numbers/ allergies/ meds for your baby. If you are ever - god forbid - in a car accident and cannot communicate, this will let Fire & Rescue/ Police know who to contact and anything they should know about the baby.
(I know, I posted about the Advanced Directives the other day... I'm just a bucket full of sunshine doom!)