I've always thought Slashdot's old moderation system was pretty well designed. It's been years since I've been there, but as I recall, there were several categ

I've always thought Slashdot's old moderation system was pretty well designed. It's been years since I've been there, but as I recall, there were several categories of upvote -- Interesting, Informative, and Funny come to mind. There was a meta-moderation system to calibrate the moderators. The site was better than HN at showing only upvoted comments by default, in case you just wanted to see the highlights. (Oh, and I think it would send email for belated replies, making it better for ongoing discussion -- something I've definitely missed here at HN.) Although the site is pretty dead now -- it doesn't have HN's advantage of a wealthy benefactor keeping it ad-free -- its original incarnation had some good ideas.