My company 9xb recently launched Neighbours United, a local social networking site for the Harrogate area. The idea is you register your address and can see who lives in your street. You can send them messages or write on the message boards for all of Harrogate to see.
It’s a great idea - message boards are categorised by area and subject so you can start a conversation about the best restaurants, or the worst builders. There’s only one flaw that I can see, and that’s in the privacy settings.

Unless you go to the message boards, you can only see neighbours on your street. If none of your neighbours have joined it’s a very lonely place! I understand the need for privacy, but the point of the website is to bring a community together - more access to that community would make Neighbours United not only more interesting but more effective too.