Not that it's going to be an "everytime solution", but have you guys ever heard of Stimtastic? I can't post links, but you it's probably the first link you'll get on google.

They make and sell spin rings, chewable necklaces and some other toys and jewelry that can help keeping your hands busy when you don't know what to do with them. Sometimes it's helps before things goes out of control and you start worrying of other people noticing it.