It is the nine-digit key to your life - and B.J. Ostergren has more than 18,000 of them. For the past four years, the 57-year-old former insurance adjuster has lost sleep to gain boxes crammed with public records, many plucked from county clerks and recorders' Web sites. They have one golden kernel: Social Security numbers, usually partnered with enough information to open a fraudulent line of credit - or worse. From her home in Hanover County, Va., she writes and calls the holders of the numbers she turns up, many of whom did not know their records were online. Her...