I’ve been working with a client on a political activism website, sort of a “Facebook for Voters”.
One feature of the website is mashups with political webservices such as those provided by Project Vote Smart to show candidates and incumbants for whom the website visitor can vote.
An obvious requirement is to know where the visitor is located, either by a location-aware service such as Google Gears, or through an address entered by the user.
In both cases, a zipcode database is a useful thing.
That’s how I discovered the ZipCodeGuy. Aside from the US Postal Service, Dave Conklin is the ultimate authority on US zipcodes. He offers detailed zipcode maps of US places (states, counties, cities).
In addition to the maps, Dave offers a downloadable zipcode database perfect for my needs. You can buy it for about $25.00. Or you can write a blog post like this one about his business and get access to the database for free. Here’s the Zipcode Guy himself explaining the database: