I think the best part about Slashdot in its best days were the people. You could be reading and article about Python and it was possible to see Guido in the comments. And while that was rare, the other upvoted comments were usually high quality from really knowledgable people and the noise was held down pretty well. As the good commentors left, all that was left is the noise. If you go now and look at comments often everything is downvoted excepted for a small number of o.k. comments. But most of the experts and really knowledgable people are gone.

HN seems to have filled some of the gap it left but I don't know of any other site since that has the same volume of really high quality content. I see some comments here blaming the inability for everyone to do metamoderation - but I'd say it was the opposite. When they had decent editors things were great. Your content will be as good as your moderators and I think reddit proves that simply having more of them doesn't assure better content.