Most of these were culled from a list of gestures on wikipedia, but they seemed like they would all make for fruitful socials. (OOC) I've tried to list them in simple terms, but some may need one-word 'command' names for implementation.
"OK" hand gesture
Air Quotes hand gesture
The Corna or Devil Horns hand gesture
Moon, for those times when you just want to greet someone in the most mature way possible
Headslap, to smack oneself in the forehead when one does something dumb
Head Bobble, an expression of agreement seen in Indian culture