I agree with shminux that keeping Main as a section one can post to is useless. I would have as places where one can post: 1) Theoretical rationality, 2) Applied rationality, 3) The Future, 4) Meetups, 5) Misc.
Then make it that ordinary posts above a certain high karma threshold (e.g. +20 or +30) get automatically Promoted to the front page, in addition to community-important things like a periodic list of meetups and, possibly, other posts at the discretion of the mods. Having Main as a separate section only causes this pointless self-callibration game in which people have to evaluate whether their posts are good enough for it, often failing and requiring posts to be moved from Main to Discussion or vice-versa.
Less Wrong is based on reddit code, which means we can create subreddits with relative ease.
Right now we have two subreddits, Main and Discussion. These are distinguished not by subject matter, but by whether a post is the type of thing that might be promoted to the front page or not (e.g. a meetup announcement, or a particularly well-composed and useful post).
As a result, almost everything is published to Discussion, and thus it is difficult for busy people to follow only the subjects they care about. More people will be able to engage if we split things into topic-specific subreddits, and make it easy to follow only what they care about.
To make it easier for people to follow only what they care about, we're building the code for a Dashboard thingie.
But we also need to figure out which subreddits to create, and we'd like community feedback about that.
We'll probably start small, with just 1-5 new subreddits.
Below are some initial ideas, to get the conversation started.
Idea 1
Idea 2