Every group is different and will decide which of the various ways members might be connected. Getting together in person is ideal. You may want to have a regular social activity and /or a regular meeting.
We are planning to develop an online platform to make communication easier between group members which will allow event invitations to be sent out, enable group discussion, allow neighbours to contact one another and to list items they are willing to share (or need).
This online tool is still in the planning stage and may be a way off, so we suggest you ask permission to share contact details and use email in the meantime to stay connected, and perhaps a google form that everyone can write into to generate ideas and allow people to indicate their interest in them. Facebook, MeetUp and Google Circles are possible tools.
Some neighbours may want to be involved but not be able to use a computer. Perhaps someone can agree to drop in or drop a note in their letterbox with anything important, such as when the next gathering is.