I brought the first Nextdoor app to the Lodge Hill neighborhood of Cambria, and through it helped to nix a nursing home slated to occupy a lot with native Monterey pines. But gorging on the community's limited water supplies was what ultimately did the facility in—thanks to the California Coastal Commission.
Yes, Nextdoor can encourage petty debates, but 2,000 households are now on it, and few "unsign." Just recently I proposed an energy-related project—to bring neighbors to a forum bringing solar to our homes now that PG&E will likely be raising rates (or going bankrupt, whichever comes first). I suggested we form a buyers club to get discounts on solar-related components.
As an organizational tool, Nextdoor is proving to be quite a tool.