&#62; Discourages people from taking moderation seriously as if it was a big deal you wouldn't be able to do it all the time.<p>I'm not sure I agree with this.  I really like the HN system whereby upvotes are free, but downvotes are restricted.  (Well, I assume that's the way it is --at least, it's easy for me to see how to do one, but not the other.)<p>This makes it easy for me to give a post a tiny bump up, so that I don't think much of it, but emphasises the cost of giving it the equivalent tiny bump down; and isn't that a good attitude to instill in a commenting community?  Certainly I think the culture here is notably friendlier than just about anywhere public-facing site (LtU (<a href="http://lambdatheultimate.org" rel="nofollow">http://lambdatheultimate.org</a>) being perhaps a notable exception).<p>EDIT:  I saw a mention of Metafilter elsewhere.  I forgot it as an example of another site with a novel approach to the commenting problem; namely, make commenting not free by imposing a small, one-time cost.