It'd be unfair to do a FTF on this one, so I'll just tell you what it is.
On a temporary/test basis, I've implemented a "Ban" feature for Premium boards. That is, boards on which only Premium members can post, which encompasses everything but stock-specific and Free-Zone boards.
If you're the chairman or a director of one of these boards, you have a link in your Manage screen that lets you ban someone from further posting in that board. Additionally, the Manage screen has a link that'll let you view banned posters and unban them.
Any user who is browsing a board that has any banned users will see a "Bans(xx)" (where xx is the number of bans) link that they can click to see a list of everyone who is banned from that board and who did the banning.
A poster can't be banned pre-emptively from a board. You can only ban someone who has already posted.
If you have a Free Zone board and would like to be able to use the Ban feature on it, ask Matt to move it to a Premium category, but keep in mind that such a move would prevent free members from posting to your board.