Interesting ideas/techniques to write about, or just new stuff in general?

This post was originally written on Codeforces; relevant discussion can be found here.

Recently, I retired from competitive programming completely, and I found myself wondering about what I’ll do with all the competitive-programming-specific knowledge I have gained over the years. For quite some time, I’ve been thinking of giving back to the community by writing about some obscure topics that not a lot of people know about but are super interesting. However, every time I ended up with ideas that are either too obscure to be feasibly used in a competitive programming problem, too technical to ever be seen in a contest, or having too many good posts/articles about them anyway.

So here’s my question: do you think there are topics/ideas that you find are interesting and beautiful, but are not appreciated enough to have their own posts? If I am familiar with those ideas, I can consider writing something on them (and irrespective of that, I would encourage you to write a post on such ideas if you’re familiar with them). If I don’t know about them, it’ll be a good way for me and everyone else visiting this post to learn about it (and if I like the topic, who knows I might as well write something on it too). Also, it’s not like the ideas have to necessarily be related to algorithms and data structures, some meta stuff like this nice post works too.

For an idea about the kinds of posts I’m talking about, you could refer to my previous educational posts. I was mainly inspired by adamant’s and errorgorn’s posts, since they tend to be really interesting (I would recommend checking them out!).