There are potentially some interesting resources at this information aggregation site for non-profit technology. I've linked specifically to the section related to community organizing:
http://www.rosetrails.org is the only one that's publicly viewable. Nextdoor requires registration with proof of neighborhood residency in order to access it, and the Google Group for neighbors on my block is only viewable to members, but it's pretty similar to a Yahoo Group.
One other thing I forgot to mention about Google Sites and Google Groups: you can use your Google Group as an access control list for Google Sites. That is, you could grant access to view (or even edit) your neighborhood's site on Google Sites by simply adding the group as an authorized viewer (or editor). Then as people are added (or removed) from the neighborhood in Google Groups, their access to viewing/editing the site would be immediately take affect.
(The other thing I forgot to mention is that I work for Google, and so my opinions may be biased. 
http://www.nextdoor.com -- I've been using this with our neighborhood, and it's a good basic tool for communication, but it falls short of promoting ABCD in so many ways. The best part is the neighbor residence validation component, which ensures that only those people who live in your neighborhood can join the group. But then a huge part of the site is for 'recommendations' of services, and yet there is no way to build associations of people within the neighborhood. They provide a directory of registered neighbors and their various interests/gifts, but no way to search or index their gifts or associations.
http://sites.google.com -- I've built our neighborhood's public website using this, at http://www.rosetrails.org. (Ok, so far it's better described as a 'prototype' at this stage.)It's super easy to edit and allow other people to contribute to either the whole site or a specific set of pages.
http://groups.google.com -- I created a Google Group for neighbors on my block for email-based discussions, and our list includes about 18 of the 36 households so far. It's great for communicating events, discussing suspicious behavior, etc...and I look forward to using it to help me in applying ABCD within our neighborhood.
It's very easy to record it as part of a publicly viewable broadcast (calledHangouts On Air). Recording a private meeting at this point is a bit more convoluted.
I haven't used GoToMeeting in ages, mostly because I use Google Hangouts instead (for work...plus my team at work runs the servers for it...!), so I don't know what the pros/cons of GoToMeeting might be...but I should probably take the time to check it out just to see what it looks like these days.
