Reverse DNS lookup & IRC-like wildcard bans
Doing a reverse DNS lookup for the client IP address whenever a user connects to the server, and allowing IRC-like wildcard bans on the resolved hostnames or IPs would be nice. Banning an entire ISP would be easy then:
"ban *.badisp.org"
"ban 125.45.*"
This would be an effective way to prevent people from simply getting a new address from their ISP by reconnecting to it.
When we're at it, banning some nicks with wildcards would be nice too, and logged-in admins should be able to use banned nicks. Ban the server admin nick permanently to restrict it to admins; ban "Administrator" etc.:
"ban *Username*!@*"
"ban Administrator@*"
"ban *@*.badisp.org"
etc.
If you fear that this syntax is too hard to understand for some admins, the new functions could be added to a new command, for example "hostban". The normal "ban" command would become a wrapper around "hostban".