What are the best ways of finding a social network of your interests? - week6

Hmm…
Reading material was interesting (as usually), but the reflection theme of this week is not perhaps the best. Maybe it is just me, but i did not find an answer to the question. I can list here what are the possibilities to find the social networks:
1. through people - you know somebody who is a member of some community or you just know some names and you will start looking for them. And then you see who is connected with whom and so you can go on.
2. through material - i read something what is interesting to you and you choose some keywords and start looking for them
3. through web - web pages of different associations, social bookmarking tools, Blogs, links, tags, ….

But: important is the ability to understand the content and assess the quality of the network (or regular web-page).

Could this week assignment be about communities of practice and learning networks? How to build it up (model) or describe a successful community of practice or learning network? Or how learning networks support learners?