When people get in a car, often a new character comes over them. Some become aggressive, fist shaking, wild drivers. George Carlin, the comedian, quipped the degree to which a person is a jerk (politely put) is directly proportional to the get-a-way factor.
Likewise, online personalities become wild and elements of peoples egos that are normally suppressed become accentuated online. There is also the problem of communication in writings as facial expression and other body language normally observed are removed from online conversations.
What kind of personalities have you seen? What is the worst you have seen? What is the best you have seen?