A second ago I read the Hex Colors topic and someone mentioned Nexuiz. That brought something to my mind. How about way point sprites? Back when I played Nexuiz, these were so useful no matter what game type. For those who don't know, way point sprites are just simple little images that say HERE, DANGER, or INCOMING. You can make different ones of course. They simply would hover over the ground of the map with an arrow below them.
HERE
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You could set them to either spawn at your crosshair position, the last place you died, your players position, or have them spawn and attach to you. They would then simply fade away after about 10-15 seconds. They would be visible no matter where you would be in the map because they attached to the sides of the screen when they weren't in your FOV.
This could help in so many ways, just a simple example:

(hall 14 in a huge ass map) : need a

in hall 14!!!!

(hall 2) : where the hell is that -_-?
Yeah it's a bit overdone, but you get my idea.
It could also help with

s, so they don't get blocked in halls.
Like a sprite saying "make a hole" or "clear the path" could attach to the rant and instant notification would go the members in the hall to move out of the fk'n way.
F1? F2? Maybe? lolwut?