My most noticeable ones are:
Pacing. I do this very frequently to activate my mind/imagination.
Rubbing or pressing my face gently to my cat's fur, or kissing him. It's part of playing for me and Krys, and I suppose I often do this when other people would stroke the animal (I do stroke him too, of course, but for some reason I can't resist touching him with my face).
Picking scabs from my fingers and occasionally feet. I've been trying to get rid of this but it'd very hard, since I carry on doing it almost unconsciously a lot of the time.
Sniffing and/or reaching with my tongue inside my throat, collecting the mucus coming out of my nose, then feeling it with my tongue before swallowing (occasionally I used to draw it out on the tip of my tongue, take it with my fingers and examine it - yes, I know, this is disgusting). I've also been trying to get rid of this but, once again, just like with the scab-picking, I do this without being aware of it.
Rubbing my eyes when trying to concentrate or when tired and/or stressed out.
Gazing at or closely examining the various objects I find visually attractive. This is very soothing and enjoyable.
I also curl/rub toes, run my hands along the fabric of my clothes (usually on my hips), rub/twist my fingers and hum/sing to myself or make noises. I must make a lot of small movements which I'm normally unaware of and which I never thought of as "stims" (or anything unusual whatsoever) until I learned about ASD.