Six years ago today we launched https://openbenches.org/ - it is a crowdsourced map of memorial benches from around the world.
Uses OSM for displaying the maps and letting uploaders pick the exact right spot.
There's an API and data-dump so it can be incorporated into OSM - but our data isn't always as precise as needed. I'm still trying to work out a way to map an OSM bench ID to our ID.
If you're out mapping and spot a memorial bench, please do submit a geotagged photo to our site :-)
I created two maps with umap for local politics in my city.
One is about cycling infrastructure: the status of a city council resolution that introduces city-wide safe cycling routes. The project is hardly going anywhere so this (and a blog) is me trying to get public pressure on: www.radmonitor-regensburg.de/hauptrouten. It includes different layers (standard is current status). Still needs some improvement in communicating the project and its message.
The second one is about maxspeed withing the city limit. There is a lot of discussion about slower car traffic in Germany. I got the existing OSM data with Overpass Turbo, exported the different speed limits and imported them to seperate layers in umap: www.radmonitor-regensburg.de/tempo30. Had to add some more data but overall I was surprised to see how well maxspeed was already documented (some data still missing but hardly anything, really).
The second project really got me started with Overpass, I use it regularly now to spot missing data and add it to OSM.
It is really great to see all the possibilities you have with OSM data and the tools around it!