- Categories can be used to model databases, and have been used for data integration. See also this paper. There's a pretty gentle introduction in chapter 3 of Seven Sketches in Compositionality.
- Coalgebras are a generalization of automata, and have provided insight into notions of bisimulation. I saw a talk about this, but also found this paper
- Closed symmetric monoidal categories have been used to model linear logic, but also to model quantum computation (which is itself related to linear logic). There's a Rosetta Stone paper that discusses this.
- CRDTs are a cornerstone of distributed computing, and while I don't understand it myself, it looks like there is some connection to category theory
- Guarded recursion and the Topos of Trees generalize step-indexing, which has been used to model higher-order separation logic. This is a tool for verifying programs with heap memory and/or concurrency, and has been applied in Iris.
I think it's also worth mentioning that the Programming Language concepts are not exactly isolated or esoteric. Monads originated in Category theory: my understanding is that Moggi (a category theorist) first applied them, and they were brought into Haskell by Philip Wadler.
But, monadic interfaces are everywhere. Errors in Rust are monadic, as are basically any langage's
And, of course, category theory is basically at the heart of modern logic research, which underlies most CS theory.