Hasn't this been tried on Warcaft 3's online community? With the program called wc3banlist
There is one "official banlist" for each realm (there aren't many, and they're based on your location, Europe has one realm for an example), and only a select few people can add people to this list, people who have proven that they won't abuse it or someting. And there are a few major "private" banlists which people usually adds to their program since the people who maintain these are well known as well. And then everyone has their own local banlist on top of that, which keeps track of all the people you've personally banned, and as such you can avoid playing with these people again.
If the point is to punish the banned people the banlist doesn't really do much, but if the point is to never play with that particular douchebag again, it works pretty well. You'd be surprised to see how often I got use for my local banlist actually.
Now I barely play wc3 anymore, so I have no idea if the banlist is still in use. But it was a helpful tool, and I'm sure it could be successfully applied to other online games as well.
If the point is to punish the banned people the banlist doesn't really do much, but if the point is to never play with that particular douchebag again, it works pretty well. You'd be surprised to see how often I got use for my local banlist actually.
Now I barely play wc3 anymore, so I have no idea if the banlist is still in use. But it was a helpful tool, and I'm sure it could be successfully applied to other online games as well.