You can hack your MySql database to allow for negative post counts.
I am an administrator at
http://www.ls1.com. I have altered 2 tables in my MySql database to allow for negative post counts. And in the control panel I have set up a new status called "Free Post Abuser" which is for post counts -1000 to 0.
Free post abusers are given -1000 post count.
Here are the mysql commands I issued to allow for negative post counts:
alter table user modify posts smallint(5) DEFAULT 0 NOT NULL;
alter table usertitle modify minposts smallint(5);