I had a conversation with my old-man recently and talked about a bit of advice that he used to give us when we were kids.
"Instead of acting on your anger," he said, "you should write a letter to the person that you angry with and don't send it but put it in your desk drawer. One week later, pull it out and re-read it. You will probably find that you aren't that angry anymore and are pleased that you didn't send the letter or say those things."
Writing down your thoughts in a ranting manner and striking out (on paper) at those that have offended you is cathartic and usually relieves the need to physically act on your current feelings.
I have a theory that blogs often have that effect and when you see someone ranting about something on a blog I bet that when they've finished ranting they feel much better. Take a look at Mando's Self-Indulgent "Ex" Rant (read at own risk) and her comment that immediately follows. I'm fairly certain that Vern feels the same way after some of the posts that he makes.
My theory is that the catharsism (not a real word) from rant blog postings stops many people from going postal. I theorize that there would be more violence if this form of outlet was not available and I feel that people who are that way inclined may benefit from having a blog. If people post comments on your blog agreeing with your comments, feelings and statements then it also makes you feel less isolated with your feelings etc. I'm starting to go off the deep-end so I'm going to stop here.
Of course if people post comments stating that you're a nut-case then maybe you are and the blog isn't working...