We use this at East Bay for Everyone to figure out which members live in which neighborhood; we then use that knowledge to strategically activate people into action. No sense in telling West Oaklanders about the community meeting going on in the Laurel, but Laurel organizers really want to know when new members join in their neighborhood.
Organizer handles that for you. Its a super useful tool for us so far. Please use it and give me bugs to fix.