I think you can sue for slander against someone. But out of my whole criminal law class, that was the part that I zoned out on lol. I think if it seriously affects someone like bullying, losing a job, or suffering a bad public perception, then something could probably be done. And anymore it seems like if you breathe the wrong way you can be sued. The usual Internet flame wars don't seem legal worthy.
I also think I have an idea of what made you ask this question too lol...all the BS today?
Yes they can but only if they caused you undue harm or stress with their words. It would be difficult to prove what they said had with sole intention to hurt you. Also you have to prove that it caused harm to your mental well being like depression or low self esteem, that would mean a certified health professional diagnosis you. Overall it would be so much trouble to do it for a random instance it would not be worth it. Like others said though if it is a recurring event that you can't get away from, it could turn into a crime like cyber bullying if the participants are under age.
Internet provides power, anonimity. I think it should be pursued (but the person shouldn't really be sued, only charged for harassment, etc.) because how would you feel if every day you came home to paragraphs of anonymous messages telling you how ugly, flawed, despised you are? Personally I would hate myself. The big difference between internet and real life is that the internet gives people a false power, thinking that there are no consequences, and they often go farther than they really mean to. If you say rude, hurtful things, you never know how the other person will feel, no matter where or how you say it.
If it's an ongoing problem where someone is being harassed online daily (cyber bullied) then yes, but not if you just call someone a name one time or whatever.
You can also do so if someone says enough stuff to be considered defamation, slander, and libel. It would have to effect their life in a way such as, you ruined their name and now they can't find a job because of that. I don't think this stuff really happens between people who have never met, it's usually high school kids spreading rumors/blogging/facebooking about classmates