It's deffinantly all body langauge, it's good when someone sits facing you, playing with there hair, or ear lobes alot, I also heard about the open palms/wrists one ...
Oh yeah and its stupid but when a girl (or at least me) waits a couple of days to call you its coz she doesnt want to seem desprit, but with my guy friends I will call them 4 times a day if I feel like it. But if I started to like that guy friend I would call him like every two days and get mad if he didnt call me.