When you view a post, now there's a little 'related' section showing similar posts. I've been wanting this for awhile, but kept deprioritizing it. Since I was already working on search, I decided to do it. The intent is to help rabbit holing on topics. It will probably need to be tuned over time, but at least on the posts I tested it's net helpful.
Hopefully over the next few days, I'll also use this query to warn users they are posting a story similar to a recently posted story.
Oh and we now redirect http://lightningtalk.org to SN. Thanks to @02d0db813f for the recommendation.