It seems like this is also overlapping with Craigslist then?

If you want to advertise anything based on location, Craiglist is free and widely used.

If you can really provide something uniquely useful to bring members then people will come. I just don't know how much local neighborhoods care. You could target neighborhood watchs, get-togethers, clubs, and, as you said, advertising.

The thing is... all of those things are available in different forms (meetup.com, craigslist, etc.).

I suppose bringing them together isn't a bad idea though. Surely if meetup, craigslist, and other location-based services work, then there is a market for this.