The USNaviguide website has an assortment of Google-Maps-based services for mapping the boundaries of various geographic parameters:
Zip Code: Enter a 5-digit zip code, or the first three digits of a zip code, and get a map of the area covered by that zip code. Or click on the map, and get a map of the all the zip codes in that area, with a placemark at the location you clicked on with the zip code for that area in the info bubble:
City/town boundaries: Enter a zip code, or click on the map, and get the boundary of the city/town jurisdiction for that area where appropriate:
County/FIPSCSA: Enter a zipcode, or click on a spot, and get a map similar to the one above for either a county or a FIPS (Federal Information Processing Standard) Core-Based Statistical Area, with a placemark near the center of the polygon with the relevant information, including code numbers.
There is also a US geocoders (get a latitude/longitude for an address), and a reverse geocoder (enter the lat/long or click on an address, and get back the closest addresses to a point).
The related Maps.Huge.Info site has links to most of the above services, but also a few more as well:
- US telephone area code maps
- Plotting zip codes by line boundary instead of overlay map (as at the top)
- Australian post codes
- A zip+4-based reverse geocoder
Finally, there’s a page of the free PERL code they use for converting a polygon of points into a Google Maps polygon.