AnyWho - from AT&T, Area Codes, White and yellow pages, international directories, reverse lookups, and toll-free searches.
Switchboard - from InfoSpace, nationwide residential and business directory
WhoWhere - from Lycos, white and yellow pages
People Search - from Yahoo, search for phone numbers and email addresses.
Internet 800 Directory - from DIANCO, search by product or service, company name, or toll-free number.
ZIP Code Lookup - from the United States Postal Service, find the correct ZIP+4 for any address or company or find a list of cities by ZIP code