The Rrove blog — no, no, not THAT Rove (different spelling) — delivers a round-up review of nine sites related to community mapping tools.  See http://www.rrove.com/blog/2006/12/04/9-awesome-community-mapping-websites/

Disclosure: Rrove.com
plays in the community mapping space. This post aims to highlight the
innovations and the usefulness that others have made in this game. We
haven’t added ourselves to this list – if you want to know more about
Rrove, click here.

A
community mapping website, in our definition, is a service that gets
its members to map and define places. Through crowd-sourcing, these
sites are building a database/directory of local and nearby locations
that their users can discover and visit. Why is this important? We all
know that search advertising is the fastest growing industry in the
Internet. Within that market, local search is the up-and-comer. In the
next few years, it will be the largest segment within search!

It’s
refreshing to see how others have approached community mapping. Some
have focused on map creation while others do it through mobile apps.
More than that, some players have mapped the community of users to map
the physical community (i.e. neighborhoods). Here’s how nine websites
(all free) are doing it, what makes them awesome and how you can use
their services in your Internet life.