To get the sort of posts that appear in the off-topic sections of forums, I think there'd have to be a specifically off-topic section, in addition to miscellaneous-but-relevant. It feels like there's some pressure in this community (though it might be only my perception - I don't think anyone is trying to pressure people) to keep posts to a high standard, so we'd need to explicitly make a place where it's okay to talk about cat videos and minor life events and the weather if we wanted to be able to talk about that. (Though there are probably other ways of indicating that it's okay to go off topic - after getting it started, having off-topic threads that don't get downvoted might be enough.)
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