There's a tellraw commnd that when used display to the players included in, @a, @r @p, or the player name.

http://minecraftjson.com/

The link aboves helps us create a command.

Maybe Pat can make it so that this command broadcasts whatever text is written to all players, nearest player. or a specific player on the plot.

This can be used for rps. Or maybe a description for a build.

Edit: /cb set message already does this. I would delete this post. But, I can't.