DirectMail.com offers a registry to get off mailing lists. Their members are encouraged to use the lists to avoid sending mail to people who do not want it. Phone numbers: 888-690-2252 (toll-free) and 301-855-1700.
For additional registries see an earlier posting or click on the subject "consumer protection" on this website.
Website cited: http://www.directmail.com/directory/mail_preference/faq.aspx
Source: Fort Worth Star Telegram article 7-15-2010 by David Casstevens p.1B