We have, in small slack bot side projects. done experimental work with web server frameworks Tide and Warp. Tide is not ready for production use (they say so, to be fair) and we’ve moved on from it.
Next up: http://rocket.rs and actix-web, in either order. These both have good docs and a more standard approach to API design, so they’ll spend fewer novelty points. I think Rocket in particular will feel very familiar to everybody.
Ceejbot's mastodon instance. This is an overprovisioned, personally-run instance running on AWS. I welcome friends to create accounts here. I intend to run it as long as people are using it.