There is a new version of chat up that will hopefully address some of the problems we've been having with unsociable behavior.
Click on a user's name in the list to the right to access one of these new functions:
1) Whisper a private message to that user.
2) Ignore all messages from the user for the remainder of the session.
Mods and Admins now have the ability to boot out disruptive users as well. Booted users will not be allowed to re-enter chat for 24 hours.
Hope this helps.
If there is no mod in the chat room, you can use the ignore button. It's as good as a boot because you won't have to see anything else that person says.