If you live in an apartment block, you'll be familiar with the body corporate. A neighbourhood association is less formal way of pooling resources and information.
Photo by Mark Baylor
Free Money Finance outlines some great ways to save money with one Yahoo neighbourhood group:
Lawn equipment. A friend who has neighbours who live in their house only part-time went in with his neighbour on the cost of a riding mower.
Contracting services. I had my septic pumped the same time as my neighbour, and we were offered a discount for only requiring the truck to visit one neighbourhood that afternoon.
A babysitter. One sitter for multiple kids usually costs less than two sitters for the same number of kids.
Think of other resources you can share. I've saved on newspaper subscriptions and taken turns shovelling driveways. Anyone can form a neighbourhood association -- just get a group of neighbours together on an email list and pool resources whenever you can.