This site includes circulation for selected magazines by gender, median age, and median income. Access to the some data via the Search feature and Top-Line reports is free with free registration. Access to the Mediamark Reporter is by paid subscription only.
"Nielsen's lifestyle segmentation systems define every neighborhood in the U.S. in terms of distinct lifestyle types using ground-breaking segmentation techniques. You can get a first look at your neighborhood using the MyBestSegments ZIP Code Look-up."