Launching a neuroscience blog is on my to-do list - although it's currently in the idle-daydream-planning stage.
I, too, looked at Lesswrong's reddit-blog hybrid format and thought it was awesome and worth imitating. However, I don't have the technical skill make any forum let alone a reddit hybrid, nor do I have a good estimate concerning how long it would take to figure it out. I also don't have any idea how to deal with spam and stuff.
Here's an intermediate coding-noob friendly solution I've been considering, inspired by the existence of reddit.com/r/hpmor
Rather than a traditional comments section, you make a subreddit devoted to your blog. You post all blog posts on the subreddit. The "comments section" consists of a hyperlink to the subreddit post. If any of your readers have anything to say, they can post on the subreddit. You can take the high quality reader posts from the subreddit and transfer them to the main blog, giving the poster credit. Reddit does all of the anti-spam stuff for you, and you just piggyback off the service. It's a mutualistic relationship - reddit assists with forum infrastructure, and your readers will become redditors. If readers is important to you, you might even get a little traffic from users cross-posting your stuff to other subreddits.
Again, this is idle daydreaming on a topic for which I have no experience, so it's completely possible that this is a dumb idea. If you know what you are doing and idea strikes you as incredibly bad or incredibly good, please do let me know.
Note that reddit closes comments after something like 6 months.
LW has a unique format. It is a forum-blog.
It is not a forum in the traditional sense. In traditional forums you cannot have long, essay-like posts (technically you can, but somehow the culture discourages it). Also, visually the top-level post appears separate and isn't similar to the comments. Like forums, you do have threaded comments and a karma system. Further, anyone who wants can register, post and comment.
It is not a blog in the traditional sense. In most blogs only a select few can post. On LW anyone can create a blogpost, as long as it is somewhat relevant. There is also a notion of Main, where the moderators select the best posts. And the bloggers can aspire to achieve the Main standard.
I feel that this kind of forum-blogs can be very useful in many domains: math, physics, meditation, music, health and nutrition and so on. Of course, we'd need to assemble a high-quality audience who are not afraid downvote and also have good moderators. The problem of assembling a high-quality audience can also be done in LW fashion. Write a good blog for sometime and then convert the format of the blog to forum-blog. The advantage is that the new people who write posts have a guaranteed high-quality audience and are hence incentivized to post and make good posts.
So here's my appeal to people who already have blogs with a good readership: please consider converting your blog into a forum-blog in the style of LW. It will be a huge service to the community. If you do so, please don't be shy to moderate and select the best and treat them separately.
Or is there some other subtlety that I'm missing which is preventing the creation of forum-blogs? Or are there already forum-blogs out there and I'm just not aware of them?
EDIT: In reply Randaly's comment, I appeal to LW's masters: please consider releasing an open-source toolkit that allows the creation of blogs based on the LW format.
EDIT: David_Gerard points out that LW's source is open.