Mob mentality: Herd behavior describes how individuals in a group can act together without planned direction. The term pertains to the behavior of animals in herds, flocks, and schools, and to human conduct during activities such as stock market bubbles and crashes, street demonstrations, sporting events, religious gatherings, episodes of mob violence and even everyday decision making, judgment and opinion forming.
http://en.wikipedia.org/wiki/Herd_behavior
I think it is possible for certain chatrooms, forums, or groups on Facebook to have a mob mentality where a bunch of people follow a leader or a bunch of high ranking members to do stuff like spam people websites with "false statements and reviews.".
I been in forums, chat rooms, and blogs where the members seem to follow the top ranking or members with the most power. I feel trolls, flamers, and fanboys sort of follow a mob mentality when posting about a topic especially members who post Awesome when they also see the other members post Awesome, great, wonderful, good, etc.