i.e., "share this waypoint that you're standing at with /". Not quite global waypoints but it allows you to share things without necessarily having everyone have access.

Like the tome of knowledge sharing in thaumcraft?
This sounds like a fun idea, maybe even split it in two:

• paper => one waypoint the user knows
• book => all waypoints the user knows

There is Bound Scrolls which can be used to share waystones, though they do require getting the item to the other player in the first place. I can see the use case of wanting to make a specific waystone available for others without having each visit manually first.

What I'm thinking is:

• Allow everyone to make a waystone public (to everyone, if you want per-player shares you'd still have to go through the bound scroll)
• Add some place in the GUI letting players view (and if they choose to, activate) public waystones
• What was previously called Global Waystones would now just be Public Waystones that have been set by the op to be activated by default

The new Sharestones should cover this use case