This is related to an earlier question I asked.
The Google Static Maps API certainly seems like the way to go given the technical constraints, however the business constraints are different and I'm starting to think there is no point where they overlap.
In short, I need to generate a map image with ZIP code boundaries, and the ZIP codes shaded in different ways to highlight some and dim others. This is obviously not something that Google has available in their API, so is there something I can do on my end to use their geocoding, their mapping, and mix in the ZIP code imagery? ...Without somehow building my own nation-wide tilesets to overlay the retrieved image, of course.
Something sort of like this, but without usage fees to contend with: http://maps.huge.info/zip.htm
Edit:
I've found the Cartographic Boundary Files but have no idea how to digest them into something useful.