You could type /dns nickname and get their IP, then ban *!*@X.X.X.* where the X's are the actual numbers within it. This will ban a small percentage of the population of AOL users and should keep your charmer out.
This works on most IRCds though I cannot confirm them all.
Edit: Nevermind, Watchdog's way is better. It's essentially the same anyway.
Last edited by zack; 29/08/04 05:31 AM.