ZeeMaps is a very handy tool to create and publish interactive Google Maps. The tool now also comes with two useful new options to highlight individual US zip code areas and counties.
To add a highlighted area for a zip code you can either specify the five digit zip code, or click on the map to automatically get the zip code for that location. For counties users just need to select a state and then the county.
Both the highlighted counties and zip code areas include the option to select the boundary and fill colors. Once you've created a region, you can make changes to it by accessing your map as Admin and then clicking on a region to modify it.