Our need to connect socially. I find this stuff fascinating. Maybe I'm studying the wrong course.

Ahh, I see now. Instead of just posting links, we can have conversations about specific topics. In this case the topic is topics! And I see we can enable email alerts which would be handy if you want to keep up to date on the conversation but aren't checking in to diigo that often.
I think I could start a topic on 'using social media as a form of procrastination when assignments need to be completed'.