Social networks, of which I count deviantART to be one for the sake of this journal, basically operate on personal opinion.
In the case of deviantART, opinion is most easily conveyed by the use of clicking on the giant, green +Favourites button on any given page of content. Recently we expanded +Favourites out to affect things like Journals, and this has been a sensible and positive change, although it met with a bit of criticism from some at first. In the case of Twitter, opinion is shared at its simplest level through Retweeting something, thereby letting all of your Followers know about what somebody said (somebody you likely agree with i