There are a lot of uses for Zip Code (US) and Postal Code (Canada) databases. I have built a few nationwide lead generation systems for large sales organizations where I use them with a little custom PHP to sort leads and assign them to right office geographically.
They can also be used to verify or pre-fill city, state and zip form fields.
Used with ‘geoip’ you can customize landing pages or sales pages to look like you’re local…
I’ve put these in SQL files and added instructions to make them easy to install.