Phone Directories

Addresses.com White Pages
AnyWho
Google Phonebook
Yahoo! People Search
InfoSpace : addresses and phone numbers for people and businesses worldwide
Qwest Dex--residential and business directories
Switchboard--"the people and business directory"
Lycos People Search

Addresses.com Yellow Pages
BellSouth Real Yellow Pages
BIG BOOK Yellow Pages--"find 16 million U.S. businesses"
Big Yellow--"find millions of U.S. businesses"
GTE Super Pages
InfoSpace : addresses and phone numbers for people and businesses worldwide
Oregon Live Yellow Pages
Qwest Dex--residential and business directories
Superpages.com

Toll Free Phone Directory from AnyWho Directories by AT&T Labs

Telephone Directories on the Web: an index of phone directories arranged by country
WorldPages: white and yellow page listings from around the world

Ancestry, Inc.--not exactly a phone directory! But another useful database to use for locating the final residence of somebody, marriage records, and lots more.