I've mentioned this system on Slashdot, and meant to mention it in my last JE. I figure I may as well write a JE on it.
There is this P2P network called The Circle. It not only has file sharing (with Debian apt-get functionality), but an IRC like chat system and a group messaging system as well. The reason I am talking about it here is the group messaging has an interesting moderation system. They call it "trust based".
Basically you move a slider according to how much you trust another user. If you move it towards the left, it means you think the person is a liar, annoying, stupid, or you just hate them. (Like a foe in slashdot.) Towards the right, you trust them, you like their posts. (like a friend in slashdot) If it's in the middle, you don't feel either way about the user. It's not a binary sort of thing. The trust value can vary in any amount you want, more than just foe/neutral/friend) You can rate individual posts this way as well.
I don't remember the exact way the trust values were calculated. More or less, the post's default was rated by how much you trust the poster. If you haven't rated the poster, then the system goes by others' trust values adjusted by how much you trust them. If that post was rated by you (or a user you trust), then the rating overrides the poster's rating. Posts with a rating below a certain threshold are deleted from your computer (so you don't have to see untrusted posts). Posts are also sorted by rating, so you will see higher rated posts first.
I think this system would work very well--they didn't have many users when I was on it, and almost no posts. Everyone can moderate. You will probably see posts you want. No one person can control the rating of a post, everyone will see different ratings according to who (and how much) they trust/distrust. In this system, you can see what others think of you. (all ratings are shown) Troll posts shouldn't last long. I believe new users have a default of neutral, so unless you go for strict a config, you'll still see them. The system also allows anonymous posting (not sure if this is good or not).
Keep in mind The Circle is still in beta and the group messages weren't a high priority, so the interface is clunky. They didn't even support threading when I was using it. Also, this type of system wouldn't work well on a web board (like slashdot). It'd probably take too much processing time.
 Update: mistake fixed