Postage Rates Worldwide  
   Current postage rates, Domestic, Europe, USA, cards and letters, in over 60 countries
   http://www.atms.ch/rates

Links to Post Office Pages  
   Links and resources for postal code and international address and address format data.
   http://www.grcdi.nl/linkspo.htm

Postage rates worldwide  
   Directory of mail rates (domestic & international letter rates) with links to the rate calculators or rate tables of postal services in most countries of the world. email rate queries supported.
   http://www.geocities.com/wallstreet/exchange/1161/

National Address and ZIP+4 Browser  
   Interactively browse all address and ZIP+4 records in the United States.
   http://www.semaphorecorp.com/cgi/form.html

SpeedKeys.com  
   SpeedKeys is a fast and easy zip code, city, state and area code look-up program. It can also generate an optional PostNET Barcode.
   http://www.speedkeys.com

United States Postal Service: Zip Code Lookup  
   Find the postal code for a United States address.
   http://www.usps.com/zip4/

ZIP Code Lookup  
   Lets you get a list of all ZIP codes in a city, county, or area code.
   http://www.getzips.com/zip.htm

Simply Zip Codes  
   ZIP code, city/state, area code lookup along with distance calculations and population data.
   http://www.simplyzipcodes.com

PostalRates.info  
   Postal rates, post codes, philately and Postal Authorities around the world.
   http://www.postalrates.info

KJL Software, Inc.  
   Databases of US ZIP Code and Area Code information.
   http://www.kjlsoftware.com/

International Mailing Address Formats  
   Includes format information and/or examples for many countries, and links to additional references.
   http://www.bitboost.com/ref/international-address-formats.html

DirectMailQuotes LLC  
   Zip code directory lookup as well as postal rates, regulations, glossary of mailing terms.
   http://www.directmailquotes.com/postalregs/index.cfm

ZIPFind's Postal Code Calculator and Data  
   Calculate distance in miles between two ZIP Codes. Find all ZIP Codes within a radius of a ZIP Code.
   http://www.zipfind.net/

Canada Post: Postal Code Lookup  
   Look up postal codes for any address in Canada. Also look up address ranges for given postal codes.
   http://www.canadapost.ca/personal/tools/pcl/bin/default-e.asp

The National Address Server  
   "Given a valid U.S. postal address, this server attempts to rewrite the address in the proper format along with the ZIP+4 code."
   http://www.cedar.buffalo.edu/adserv.html

Standard US Postal Service Abbreviations  
   Lists the correct abbreviations for each of the states to be used when addressing envelopes.
   http://www.princeton.edu/Main/postal.html

zipdecode  
   Java applet which maps United States zip codes on a map, reducing possible matches as the number is typed.
   http://acg.media.mit.edu/people/fry/zipdecode/

Free ZIP Code Lookup  
   Free United States ZIP code lookup. Listing by zip codes or state names.
   http://www.downloadzipcode.com

Zip-codes.com  
   United States. Includes some statistics and histories of the post office and of the development of the ZIP (zone improvement plan).
   http://www.zip-codes.com/