Policy re comments

I need to ask some people to use a little common sense in posting comments here. I normally greenlight everything that isn't either commercial spam or potentially defamatory. What is defamatory? Going after particular individuals, especially by name, and accusing them of crime or other such activity. Please, people--use some common sense, OK? If you want to libel people on the web, get your own blog, and then you can defend yourself in the ensuing libel suit.