From Carlos Loth’s blog: Brazilian’s postal service publishes a web service to allow queries from Microsoft Office 2003.
It works like magic on Word.
I tried a quick and dirty approach to make it work from within a .NET application without success, but soon someone will figure out how to do it.
In my opinion, the postal service should open the zip code database since it’s a government owned company. For that reason it should publish the database as a web service instead of charging us for a CD-ROM subscription.