LonerVamp of terminal23 has written a nice blog post about anonymity on Internet Relay Chat (IRC):
staying anonymous – part 4 irc
I left some additional comments to it that should be approved any moment now 
. Anonymity is harder than configuring your client to use a proxy, and LonerVamp does a good job of conveying that. It’s a matter of changing your behavior, and becoming tuned to recognize identifying characteristics of what you’re doing, and modifying them. You should always be looking for ways that you might blow your own cover and prevent those situations from happening before someone else comes around to blow it for you. IRC’s a great protocol to think about anonymity in, since there’s such a host of technical and social problems that might make things difficult.
Maybe I should start my own multi-part series on “Blowing Up People’s Anonymity” .
You know, that’s not a bad idea, blowing up people’s anonymity.
Of course, the tactic of posing as a girl on IRC will likely still work quite often!