Looking up
When a person looks upwards they are often thinking. In particular they are probably making pictures in their head and thus may well be an indicator of a visual thinker.
When they are delivering a speech or presentation, looking up may be their recalling their prepared words.
Looking upwards and to the left can indicate recalling a memory. Looking upwards and the right can indicate imaginative construction of a picture (which can hence betray a liar). Be careful with this: sometimes the directions are reversed -- if in doubt, test the person by asking them to recall known facts or imagine something.
Looking up may also be a signal of boredom as the person examines the surroundings in search of something more interesting.
Head lowered and eyes looking back up at the other person is a coy and suggestive action as it combines the head down of submission with eye contact of attraction. It can also be judgemental, especially when combined with a frown.