Neighborhood wireless networks were largely championed by the Community Wireless movement that was quite active in the early 2000's. But the movement seems to have lost a lot of momentum, perhaps due to the heavy-handed tactics employed by commercial firms and the "free wireless" projects sponsored by Google. But some of the info lives on in various websites.
If you're looking for a lower-budget solution, you should check out the various "Community Wireless" sites. NYCwireless has one of the better organized sites, but you should also visit the Bay Area Wireless Users Group and Seattle Wireless.
NewburyOpen.net has some interesting white papters including a detailed spec for its community wireless setup in Boston and one describing a "Urban Hotzone" Business model. (email address is required to download either)
Also, check the links in the Community Wireless.org and DailyWireless.org sites as well as these articles:
- A Wireless Long Shot
- I Network, Therefore I Am
- BAWUG Outdoor Access Point Enclosure