Some projects that I remember that uses Ruby that are not related to web dev: Homebrew, Metasploit, Vagrant and Jekyll.
I also find Ruby very useful for shell scripts. I wrote a blog post about that some months ago, you can read it and the discussion about it here: https://news.ycombinator.com/item?id=40763640
https://www.amazon.co.jp/dp/4774176435
Before Ruby, my preferred fun language was Perl. Ruby is like Perl but without having to type $ all the time. I have never used Rails.
I think the reason it's not talked about a lot is mainly because Rails overshadowing it and because there aren't so much hype or controversies around it.
Yes it's not Ruby but it has good design, optional type annotations.
It's actually the language of choice for a lot of OpenSUSE projects as well, like the Open Build Service.
The reason you don't here much about it is because of its maturity.
However, Ruby doesn't make sense to me as a general applications language (Swift & Kotlin have won me over from C++ & Java), or as a systems programming language (I'm still rusted on to C, pun intended), and I remain super ambivalent about Rails despite using it extensively to stick web interfaces onto things. That doubt is in large part because Rails frequently undermines the Smalltalk-ish heart of Ruby.