A simple addon that adds hitmarkers and hitsounds to indicate attacking players a hit (similar to Quake 3 / CoD).
You can use different files to distinguish between normal hits and headshots (built-in hitmarkers are white for normal hits and red for headshots).
Every player can set their own preferences and save them.
You can easily add your own hitsounds (hitmarkers are a bit harder to make though).
Look into the forum thread: http://forums.eventscripts.com/viewtopic.php?f=27&t=47458