This one is new. Couple days ago I released @everydoor 5.0, and for it I made a new thing.
GeoScribble takes inspiration from OpenStreetBugs, which was where we put our OSM notes before 2013. Just a simple server with no auth and a few fast endpoints.
https://wiki.openstreetmap.org/wiki/GeoScribble
The idea is, you draw lines and leave short notes on the map. Just like with walking papers.
I see it already being used in multiple countries. The layer can be added to @josmeditor and Rapid, or browsed online.
@zverik @everydoor @josmeditor wow, that looks like it can improve the editing workflow a lot