A while back I started watching for distance markers along the highways. Here there's one every 1 KM on both sides of the road, both showing the distance to the capital city. There's three highways going out of town and all three have them.

Originally I was tagging them with something like:
distance_marker=5K

But lately I learned about tagstat and tagwatch, which allow us to check a tag and see how it's being used by others and what's the most popular.

I noticed almost 400 uses of distance_marker=yes and very few uses like mine where the name is used as the tag. So I decided to fix mine so they match that format since it makes more sense and is more flexible. (It's also recommended in the distance_marker discussion page)

So here's how I did it with JOSM. First of all I used tagstat to download the distance_marker=yes set and see how it was being used. Instead of putting the marker text in the distance_marker tag it's put in a name tag.

I then downloaded my editing area to make sure I had all my old distance_marker tags. Next I used JOSMs new filter dialog and filtered distance_marker. This has the effect of hiding all distance_marker nodes, I then checked the box marked "i" which inverts the filter, hiding everything else and showing only the tag I want to see.

I then selected the nodes one by one and added a name= tag so instead of distance_marker=5K I now have:
distance_marker=yes
name=5

Since KM is the default measurement here and in most of the world I decided to remove the K, this also more accurately shows what's on the signs.

So consider adding the distance markers in your area. On a stretch of highway they can be valuable landmarks and help people find out of the way addresses and locations. On a map they would give travelers a good sense of where they are on their journey with less worries that they've taken a wrong turn when they can match the road markers with exactly what's on their maps.

When there's a little more consensus or I find a good tag for it I'll add the city that the markers are counting from. Let me know if you have any suggestions.

Once a larger number of the distance_marker tags show up in the database it will start being added to the renderers and exporters.