I'm not sure if anyone has suggested this yet, but...
it would be an even more useful hack if it would also (optionally) let you make certain IP-addresses be miserable, instead of users/usergroups.
Why? Suppose you have 2 members, who live in the same building. One of 'm is an ass, the other is fine. If you only block one user, they're likely to figure out that you made *some* sort of change to his/her account. If you block their ip address(es), they'll not know why and reckon it's an ISP/routing problem instead (because that's far more likely then).
Can be WAY more effective, that way ^_^