My dogs know hand signals as well as voice commands, I've always found it useful in case I lose my voice, or they lose their hearing. I've also taught them some of my facial expressions, so if I snap my fingers once, it means look at me for direction, then I give them a look, usually to warn them to be on guard around a particular person if I don't want to say it out loud.
They know sit, stay, down, up, wait, stand down, all clear, to me, enough, now, halt, away, there, drop, no biting, silence, calm, easy, steady, leave it, now, help, friend, enemy, on guard, guard x (eg, guard DS), inside, outside, nobody past (as in, don't let anyone past this point), bring x or y (an object, or get a person).
I think that's it. Ddog3 is still learning them all (rescue pup) but she's very fast and eager. Ddog1 and 2 are brilliant at them. I've really enjoyed training our dogs, I don't get them to do tricks, but I have done some schutzhund work with them from time to time.