Maybe a drop-down box with a few broad categories for "Why did you vote this way?" on every upvote or downvote so the commentor receives better feedback? It seems to me the system, while it has its value, is still often times just "yay!" or "boo!" buttons. Maybe you could devise something better?

My impression is that Slashdot had a system like this, but it didn't work very well and wasn't copied by many other places.

One thing that seems likely to happen is karma weighting. StackOverflow does a similar thing, where new users can't vote, and users with sufficient karma can. One can take this further and give higher karma weights to more established users; if, say, Eliezer upvotes something, that should probably result in more than one upvote.

But this assumes that every Eliezer upvote is the same, which probably isn't correct. An alternate idea is to talk about what part of the voter is approving or disapproving of a comment. If someone says "I, as a technical expert, think this comment is good," that conveys useful information in a way that "this comment is good because it is technical" doesn't, and it's easier to control who has access to what buttons than whether people are using those buttons correctly.

LW could have some value as a meta-level "hub" site for the rationality blog universe.

I think this is a huge part of the LW value proposition.

Get rid of the Main/Discussion dichotomy altogether. It's super broken.

I agree that it's broken but there are two important constraints to keep in mind when modifying it:

1. Don't break links to old LW articles.

2. Make the desired level of scrutiny for a post obvious.

Doing the former is a question of how the codebase is set up (but it looks like both main and discussion articles have the /lw/___/article_name/ structure, so this should be mostly okay).

The latter looks to me like it's better accomplished by something like tags and background colors / textbox borders than separate subreddits.

Or maybe just organically let posts that get north of X upvotes be marked with a "This is good stuff" status star and place them in a more prominent spot.

My current thought is that a good solution to this problem also attacks the specialization problem and uses tags to a big degree; it would be neat if someone could use LW as something like an RSS feed, where the tags for a post or link modified its karma ("show me all posts with at least 10 karma, give high-scrutiny posts an extra 5 karma, give animal-rights posts an extra 3 karma, and give math posts negative 10 karma" results in them still seeing exceptional math posts and mediocre (or very new) high-scrutiny animal-rights posts).