I don't own an iPhone, so I don't whether this feature already exists, but it is something that I would like to see implemented if it hasn't already. Since people so often lose or destroy their phones and lose the numbers stored in them, I would like to be able to sync an iPhone with a computer and have all of the stored numbers saved in a file in the computer, which can then be restored to a replacement phone in case of loss of destruction of the first phone.