For me, as a professor and a media critic, online communities are a wonderful opportunity to engage with other scholars, researchers, and interested commenters (from any occupation, not just academia) who are discussing topics that matter to me. Online conversation, even when I am just lurking, helps me to understand the perspectives of people I might otherwise never meet, and consider opinions with which I may or may not agree.
Years ago, when I was a management and radio consultant, I traveled all over the US and Canada, and I was able to expose myself to a variety of opinions. But these days, my work and my health keep me in Massachusetts. Nice place to be, but most of the folks I encounter are blue state liberals or Republican moderates. In order to broaden my scope, I need to find ways to hear from people who think differently, not just those whose views are similar to mine. I take the philosophy of the late great Emmanuel Lévinas very seriously-- he encouraged us to "look into the face of 'the other' "; that is, to make 'the other' more real, more human by communicating with them. If I can't be in a room with everyone who sees politics or media (or whatever else) differently from how I see it, reaching out online is the next best thing.
Social media, like Twitter, can be a fun way to reach out too; but the 140 character limit makes rants & talking points and insults too easy. At their best, online conversation groups can provide a space for new ideas, and make interaction and critical thinking possible. Of course, the problem is unmoderated groups where trolls can take over; or groups where everyone is similar and a sort of groupthink sets in. Still, I figure it's better to engage than to remain on the sidelines. So here I am! (And I'm glad you are a Rush fan. Being a part of their story is something that will always be special to me.) So what is your experience with online groups?