The only two communities I am currently active in right now (other than career/family communities) are Less Wrong and Unitarian Universalism.

In the past had a D&D group that I participated very actively in. I think that the people I played D&D with in high school had a very big and positive effect on my development.

I think that I would like to and am likely to develop a local community of people to play strategy board games in the future.