Boston Streets: Mapping Directory DataThis project, called "Cowpaths" after the legend that the crooked streets of Boston were laid out following cow paths, is the most sophisticated historical GIS project mapping directory entries.
The site explains, "Cowpaths is a map-based tool for discovering image and directory information and then plotting it on a map. You can also discover names, occupations, and images in Cowpaths and find them in the directories and images in the Tufts Digital Library or at the Bostonian Society."