I've been for an IP (infraction point) system any time that it's been mentioned, and I like the examples of points and time-frames that Tned has laid out. This would in essence give a three-strikes and your out type of philosophy for major issues, but minor ones would be more-or-less a slap on the wrist. . .only adding on to major issues if there are any.
I would add just one other idea from my experience at the Freak. You should add an additional infraction (I'm not sure what level, but probably along the lines of 5 points) for starting a thread, or questioning publicly any infraction's handed out. Nothing causes more problems imo than a bunch of threads running around criticizing the mods actions.
That's not to say you can't question an infraction in private through pm's with the mods and/or Tned. There's just no need for the public airing of dirty laundry.