I think I'm the person you're referring to with a -6 rating, so as you can imagine, I don't think it's a very fair system! I think I've helped alot of people on this board over the past year so I am extremely frustrated to have this negative rating beside my name. It seems to be the case of someone having a grudge against me or deciding to take out their frustration on me yesterday since it all seemed to happen in one day, particularly after someone made a negative comment about me that has since been deleted.
I initially thought the rating system was a good idea because post counts don't necessarily tell you alot -- a person could have a high post count only from asking alot of questions, or even posting alot of irrelevant comments. But the system wasn't set up very well since initially, a single person was able to rate you every 6 minutes! Now you can only rate a person once every 24 hours which seems more fair. If it's used fairly then I think the rating system is a good system but obviously if people are going to abuse it for their own personal reasons then I don't think that's fair at all.