Big pet peeve of mine since I noticed it was that the compass in ArmA2 by default uses the out dated 1/6000 mil markings on the compass. This was the Soviet standard.
This mod gives the proper 1/6400 mil markings!
Just install like any other addon, and it will replace the current compass. It works with the other compass mods like the AT GUI magnifier as well.
Have not tested if it has problems with signed servers, it has a key, but I am not sure if it will be blocked.
Download link: http://raceriv.com/arma2/mil64_compass.rar (Feel free to mirror)
Armaholic Mirror: NATO Mil64 Compass
GDT Mod Compass, their compass config helped me out, and saved me time from digging through the massive UI config. Thanks a lot.