I've seen derogatory names used in face-to-face communication. I don't see how a forum would be different, whether real-name or anonymous.
I think Snort's points are a good base line:
* no derogatory names
* comment on the action (or the opinion) - don't comment on the person
* don't deviate from the thread.
I'd add another two:
* be prepared to justify, substantiate or recant any "facts" presented.
* don't expect others to do research for you.
with proportional sanctions for repeat offenders (and possibly an exception for Off-Topic).
site for some possibilities (though I think their commission is way too low).