For businesses built around a local community, understanding where your customers live can be useful, for helping to identify clusters of critical mass, as well as areas you need where you are under-represented and thus need to market more.
The above map shows 260 or so Realm of Music listeners and collaborators (e.g., musicians) for whom we have post codes (many others prefer to communicate with us by e-mail), and shows a tight cluster around St. Albans, as well as a less dense cluster in London, with a few scattered elsewhere.
The following two maps show close-ups of the St. Albans area and London, showing the dispersion within these clusters. Again, click on either map to see a larger version:
There are lots of possibilities here. We are looking at colour coding the pins by different type of customer (e.g., spend level, market segment). Also, we are looking at using the longitude and latitude to find the "center of gravity" within each cluster.
Thanks to Google for providing this powerful capability, and to Tom Anthony for pointers on how to use it.