[The Lettonian]

Try looking up specific ones, as they do change slightly from service to service. For example, the Brits and the Americans have slightly different signals for "Unit Commander" or "Lieutenant/Leftenant" - in the US it's two fingers on the upper arm, whereas it's two on the shoulder in the UK. That is, of course, if memory serves me correctly. Seriously, this is nothing you can't find via google or make up on your own. We developed a signal for "HOLY S**T! F****NG SNIPER!" for crying out loud....cross yourself, then place right thumb inside of left fist (pinkie side), and then withdraw downwards, as if left hand is crapping out your thumb. Then push right finger into left fist (index side) and pump two or three times. Finish by putting right hand up to eye as if to hold sniper scope. Point in direction you suspect they are, all the while mouthing "holy shit, fucking sniper over there!!"

Or go out and buy a book. Or find the US Marines training manual on the net.