I've also noted a raptorial wave that means they're about to jump or at least run upward, in several species; in some of my more friendly guys this seems to evolve into "I want to go up/on your hand, bring it over here." Russ has his double shield "trained" to do loop-de-loops from upright on one hand to upside down on the other. Hours of entertainment.
The head tucked with raptorials tight against it seems to be an alarm reaction or at least "I'm not so sure about this."
I have a couple who check things out with their antennae forward. My gambians and ghosts' antennae are always vibrating.
I've also gotten to where I can tell when they're looking for water, they kind of flatten out and check out the surface they're on.
Having some kept communally is definitely an education in body language. I'm fascinated that there are some things that seem to be consistent across species and some things that are a little different. Flower species and cone-eyed species are definitely more interested in what's above them.