Telephone Directories

U.S. Residential & Business Directories
Anywho: Find people, businesses, 800 numbers, or reverse lookups
Infospace
Lycos
Switchboard
Telephone Area Code Finder
Ultimate Whitepages
WorldPages
Yellow Pages

International Telephone Directories
Infobel: White & Yellow pages for western Europe
Telephone Directories on the Web: Online phone books from over 170 countries

Professional Directories
Lawyers: Martindale Hubbell
Physicians: American Medical Association
Findlaw: West Legal Directory