I wish them the best of luck.

Personally, I don't want to connect with my neighbors.

I actually commend Josh for taking the time to lean forward into helping with a very hard real-world user growth problem.  As we learned the hard way at Epinions, the people who are super into home stuff (esp safety-related) tend to be stay-at-home moms of below-school-age children and retired people.  Not only do these groups tend to not be high on disposable income, but they are entirely disconnected from each other.  Also once your kids are old enough to go to school, their school community becomes more relevant to you than your neighborly proximity, particularly for high-income neighborhoods with a lot of kids in private or otherwise competitive schools.

It's not a user-growth problem I would care to tackle myself, but best of luck to our homie Josh!

More details:

http://pandodaily.com/2013/02/12/nextdoor-snags-the-david-sze-endorsement-and-his-largest-check-ever/

David Sze says in that article:

Nextdoor is the most exciting opportunity I have seen since (Facebook and LinkedIn). It has all the early hallmarks that drew me to LinkedIn.

Sarah Lacy adds:

Sze invested in both LinkedIn and Facebook, so he’s seen a lot of what has worked well in social media. But not everything he’s touched has turned into a public company. He also invested in Digg, so he’s seen what happens when thinks start promising and go south. Greylock invested a small $2 million in Nextdoor at its last round, so Sze could take a closer look at it. Apparently, he liked what he saw. He put $15 million into this deal — the single largest investment he’s made in any company.

The crime part of NextDoor reminds me of http://www.crimemapping.com/...

And a little bit also of http://www.meganslaw.ca.gov/