Killing Spree Announcer is an easy to use addon which yells out headshot if you kill an enemy player. If you kill another player within 30 seconds then double kill will be announced. If you keep killing targets within 30 seconds more sound files will play. The last one is really funny, but you have to get over ten kills to hear it!

This is not what it appears to be by the name, it's a sound addon that will play sounds everytime you kill things. It works like counter strike, you have a certain amount of time or else it will reset and not let you hear the next sound. I.E. if you kill two things in rapid succession you'll hear: Headshot!... Multikill! and so on. Also this addon will play a sound when you are killed, some of which are down right hillarious. Type /klist help for options in game.