- Twitter is still a very small world. That person you just called a cunt, and invited to commit suicide? There's a good chance that someone following you knows them and will be more than a little upset at what you've said.
- Twitter is public in the worst possible way. It's true that most people won't pay any attention to what you've said and it's almost possible to assume that you'll only piss off followers you were best off without anyway. However, the only people who will see the whole argument are those who follow you both, and they might not want a screen full of their friends hurling abuse at each other.
- Twitter is not the context. Everyone sees their own stream and their statements are not taking place in the same environment as your statements. Twitter's weird in that the pool of people whose comments we read and respond to, particularly indirectly, is not the same as the pool of people who read our commentary. Brevity means that we can't introduce our remarks by explaining what prompted them. Anything anyone says is likely influenced by a lot of other stuff you've not seen, and it's not for you to judge whether their irony, sarcasm, hyperbole, self-deprecation, or outright venting was appropriate or not.
- A lot of that anger you're feeling is because someone who doesn't know you has had the barefaced cheek to misjudge and insult you. Their anger is most likely rooted in the same feeling. The mere fact that you're in vague communication with them means you have a lot in common with them compared to the majority of the population, so refrain from projecting too much hatred onto them.
If, like me, you struggle to keep you cool and maintain a sense of perspective during online disagreements, stick a bit of Bill Hicks on the wall by your screen:
"Today a young man on acid realized that all matter is merely energy condensed to a slow vibration, that we are all one consciousness experiencing itself subjectively. There's no such thing as death, life is only a dream, and we're the imagination of ourselves. Here's Tom with the weather."*Essentially trying to do this, but without the superpowers: http://xkcd.com/438/