Your question is not a very elaborate one.Are you a guy or a girl?In anycase,you are the best judge of what the touch meant.From a 3rd person's point of view it might as well be a harmless brush of a hand or a finger.But then you know it better.
It most generally means they are interested in you and want you to like them.
when someone touches you on your arm when in a conversation.what does that indicate.
I don't think it means anything really..its more annoying than anything else
Something that is not supposed to be in your ear - is in your ear!
I look at it like this : Arm Could be a friendly gesture Chest she thinks your sexy Stomach she wants to be In bed with you think about it.