On Nextdoor.com, Social Networks for Neighbors - NYTimes.com

 A neighborhood-scoped social network -- sign of the times (and perhaps an inadvertent beta test for future Facebook features)

"Nextdoor’s interior pages are private, unlike those of some other neighborhood-themed Web sites In a Nextdoor neighborhood, everything, including the directory of members, is visible only to fellow members, so marketers can’t vacuum up names and addresses. Nor does the information appear on search engine results.
To keep out interlopers, Nextdoor requires new members to prove that they actually live at their claimed residences, either by allowing a one-cent transaction to be processed on a credit card tied to the address, by having an existing neighborhood member vouch for their identity, or by other means."

On Nextdoor.com, Social Networks for Neighbors - NYTimes.com