Think of how many times you've asked someone for their coordinates? Its probably a lot. Or maybe you've asked what the coordinates of something are. You can just put it in chat and it'll be done. You both press F3 and have to stare at an a bunch of numbers and then you're on your way. What if I said there was an easier way? One where neither of you need to even see your coordinates.
If that sounds good to you, then this is the mod for you.
Using this mod is simple. Simple type: "/shareCoords" followed by the user you want to share you location with. There is tab completion so feel free to take advantage of that. You can also add two more integers after the player name to specify an X and Z coordinate, just in case you don't want to give your location but something elses.
To remove beacons on your screen, simply type "/clearCoords" and they will all go away