More Turing-completeness in surprising places

After Rule 110 nothing can surprise me about Turing completeness anymore.

I'd like to see more writeups on Turing-completeness in a certain situation and a usable alternative that's Turing Incomplete. There's a lot of discussion of the problem with little of the solutions. This is important as busy IT people or even hobbyist coders Google for solutions they can incorporate into their code.

I'm doing my part working from someone saying System F was Incomplete along with its Haskell tie-in that removes that. Collecting papers on extensions, transformations, certified compilation, FP compilation, etc. for people trying to build on that in the future. Still push state machines with interface checks for imperative style as that worked in high assurance development.

Other than that, what can I do about the problem in all its manifestations? I'm not a domain expert in the problem or the spots it appears. Don't see much in solutions outside LANGSEC teams or prior work from high assurance (eg interacting FSM's). Need more work on alternatives instead of just spotting Turing Completeness and developing demos of it.