I'm trying to make it a habit to write something here every day. Today, I don't really have much to say so I thought I would share instead.
I'm making available for download a KML file of all US zipcodes. KML is a file format designed to represent geographical features, such as geographic boundaries. Zip codes are the US postal codes, first introduced in 1963, of which there are currently over 42,000. This is useful for anyone trying to create visualizations or for use with other GIS systems. Here's what it looks like when opened in Google Earth:
warning: you'll need a pretty fast computer to render this
It was created by mashing together shp files from the US Census Bureau, which are provided on a state-by-state basis. I used FWTools to convert these shp files into KML files, and to join them all together.
update (12/2013): it looks like the original state files are no longer available at the URL.
I hope that this saves somebody time someday!