AT&T Labs provides searching for telephone numbers, reverse lookups, email addresses, home page URLs, fax numbers, toll free numbers, and addresses.
Infobel World - Telephone Directories on the Web
"This is the Internet's original and most complete index of online phone books, with over 400 links to Yellow Pages, White Pages, Business Directories, Email Addresses and Fax Listings from over 170 countries all around the world."
Internet Address Finder
This directory of nearly seven million email addresses is available in English, Dutch, French, German, Italian, and Portuguese.
Internet 800 Search
Search in English or in Spanish for toll-free numbers.
People Finder Guide
A research guide to finding sources of information about people.
Verizon's national white and yellow pages, also offering links to other countries' online telephone directories.
Search for people, email addresses, businesses and Web sites.
Telecommunications Service Providers Directory
The first online directory service for the mobile community.
http://www.theultimates.com Simultaneous consultation of several online white and yellow page and email directories; also permits reverse number searching.