i pace around while im thinking/deciding something. i walk into the center of every room and back out again on a continuous tour of the house (pretty much only if im home alone).
sometimes when im alone and smoking/working/bumbling around i still make comments and jokes out loud for the benefit of the 'invisible' audience (ghosts, aliens, whatever who knows im just a jackass and enjoy the sound of my own humor)
if theres no music i talk to myself in the car (actually do a lot of serious thinking in the car), or if there's music i sing along to the vocals and music. if you heard a stand-alone tape of me listening to Mr Bungle's s/t i would surely be committed.
i gotta have my morning internet/bong time before work
i fidget with small desktop items (lighters, click pens, bottle caps, anything else)
i often finger tap drums to the beat, or if theres no music my own beat or to a song in my head, especially when waiting. i probably look bored or impatient but im just spacing out in tune-land. if im sitting i tap my feet.
i think my only borderline OCD thing i do is sometimes at work/home i check locks that i know i just checked a few minutes/little while ago. i dont always trust my stoner memory.