Decline in popularity aside, Slashdot still reigns supreme as the best 'format' for online discussion. I have to hand it to the creators for sitting down and thinking through how to do moderation and anonymity. Reddit seems to have just re-invented PHPBB and all the other forum software with this.
-1 to +5 limits bandwagoning. I've seen stuff recover from initial -1 to 5, on Reddit once the bandwagons and bots take over it's near impossible for a post to change the direction.
Limited voting rights. Random moderation points. Meta-moderation. Even something as simple as not being able to moderate and comment on the same thread. 90% of Reddit is "I disagree, I'll downvote then tell them why they're wrong".
AC accounts are all equal. No account needed in the first place or a simple checkbox if I am logged in. (Plus some hilarity of "I'm posting AC because I work for..." and then they forget to check the box.)
In the golden days browsing at +4 was nothing but decent discussion of tech topics. (Or people complaining about how that isn't news for nerds). Sure the trolls show up and people have been screaming about GNAA since I can remember but they're quickly down to -1.
If there's someone that I find insightful or hate I can friend/foe them *server side* and moderate a bit further.
It's not perfect but given everything that's come along since then it's still better.
I wish someone would give the codebase a good rinse and expand it to more news discussion. It's not Reddit, Facebook, Digg or anything else that I've found.