WASHINGTON -- Customized mass-mail campaigns from groups on the left and the right are using peer pressure to get out the vote by comparing recipients' voting records with those of their neighbors. A first wave of mailers from a conservative group has spawned complaints about invasion of privacy and intimidation. More than 2 million registered voters around the country recently received flyers in the mail from Virginia-based Americans for Limited Government. The "vote history audits" in the mailers show whether recipients made it to the polls in the last several elections, and list neighbors by name and address with their...