I'm really glad that people are experimenting with commenting systems. There have been better systems in the past than Reddit or HN (such as Slashdot & Kuro5hin). Some ideas which could be explored again:

* Whether you should be allowed to both post comments and vote on a single article.

* Whether you should have a limited or unlimited number of votes per day or per article.

* Whether established users can apply multiple up/down votes to a comment.

* Should votes happen along other axes than up/down (eg. "Funny", "Interesting", "Relevant"<->"Off-topic").

* How could meta-moderation be made to work without it seeming like a slog to review other people's voting?

* Can we see who voted on a comment?

* Can we display comments in a more relevant order? At the moment the highest voted top comments are spread down the page, mixed in with lower voted replies.

* Should there be a limited or unlimited range of voting? Is a -15 comment substantively different from a -20 comment, probably not.