I didn't see any posts about the ability to tag posts or make comments under replies/posts.
Here is the case for why those are good features to have:
TAGS
-When moderating a big ol' Stackexchange forum, I'd often just tell people "click on the --blah-- tag to see all the posts on --blah--". This is more reliable than using the search function for everything, which brings in a lot of random results that happen to use that word.
-You can have way more tags than categories, and as a forum grows there will be more and more user navigation done through tags.
-Tags just worked, really well, for Stackexchange.
COMMENTS
-Commenting lowers the barrier for posting on a topic. If I have a minor comment I'd rather say under the reply "hey, good point, but have you considered x" or "here's another example of x" or "nice to see you Mr. X!", rather than make a whole new reply.
-Comments lead to other comments, which leads to cool comment threads under popular replies. This makes it a good mix of linear and branched commenting.
-Comments can be up and downvoted, which encourages participation even at small levels. Less commitment to a big reply with still some reward. Witty but short comments help conversation develop.
Tags is something we're looking into within this next minor version (in a more macro sense: we're looking into a better definition of categorizing topics, be it subcategories from a traditional forum sense or tags as per the latest trends in this space)
As for your second point, I think we already technically support this in the API, just would require a bit of a change in templates and of course a few modifications via plugins to make that happen.
It does sound like there's a bit of a demand for tags so we will look into this.
EDIT: also, pinging @a_5mith from this conversation: https://community.nodebb.org/topic/1347/extending-markdown#9833
@psychobunny Woohoo!
"Tags are per the latest trends" sounds good. Multiple, optional tagging.
As a spoiler, all my suggestions are sorta ways to meld NodeBB with StackExchange. It's basically, in order of magnitude: badges, tags, comments, reply sorting, best reply.
I'm too excited. Might have to start learning node.js. I can google this, but is there something (like codecademy) that everyone uses to learn node?
EDIT: I see code school has a course. Might pony up the money.
Haha. I might be the wrong person to ask. You wouldn't go wrong making a new thread about this - I'd be interested to know how people have gotten into Node.js. Not being a completely unbiased individual I would recommend that you learn Node.js by installing your own version of NodeBB and building your own plugin, using one of the existing plugins as a sample... 
@psychobunny Nice try 
But really, it may happen sometime this summer.
"How I got into Node.js, with existing JavaScript experience"
I installed a local copy of NodeBB and hacked a Shoutbox into the core. Than after a while I started trying to get it as a plugin, in which I eventually succeeded. I used existing plugins as a base.
I've never actually researched a thing about Node.js. Except clientside requirejs. Everything I currently know is from plugins and PR's.
I'm doing the JS path on CodeSchool for uni credits though, and it has Node.js in it, so that's a plus
@psychobunny ping not received in notifications. 
@a_5mith @psychobunny A couple notification didn't show up for me today as well.
@a_5mith @Kamal-Patel Mention notification pings do not show up when you edit a post, only when you create a new post. This is because I don't store "who pinged whom" in the plugin, so it would be trivial to just continually edit a post in order to ping lots of people over and over again, sort of like a post bump, but worse, since it's a notification.
There are a few great thread examples on this forum where comments would be a nice feature...
...Like here, where the topic of poutine is interspersed within the normal conversation, and it could instead be a couple comments within the original poutine post.
...Or [here](link url, the "introduce yourself", thread where it might seem out of place for the user to read through and see a reply to an introduction from several posts above. Some of the intro posts are beefy enough to deserve a bunch of comments underneath them.
I know comments can be made as a plugin, so I'll try to learn javascript a bit better and some node.js and help out in a few weeks/months!
Here's someone talking about how expandable comments reduce usability compared to smaller always-listed comments:
"When the big site redesign happened the useability of the site went into the crapper. I don't waste my time expanding comments under answers. Many good things are lost when embedded under answers and not seen. Who wants to click to expand comments? Not me. I think the problem is directly linked to this clunky comments and answers system. It non-standard and I don't like it."
I too think a comment (reply under reply) feature would be extremely beneficial. It doesn't have to be fully threaded, just 1 level under a top level reply is enough.
This would make NodeBB even more perfect as a blog commenting system too as blog commenting systems such as DISQUS have this.
If you start threading one level, then it needs to go another level when that quote or reply receives another reply or a quote. The one thing I despise about reddit is the layout of the comments and how they just get levelled down, until eventually it stops giving you the replies and tells you to open another page to view them.
List view, all the same. Nice and simple. Winner.
If not threaded comments, maybe a control next to the @name_of_person_replied_to that will zoom you up to the post that was being replied to.
Another idea is to have an alternate view. A control that when you click on it, rearranges everything as nested comments.
