BODY LANGUAGE

Body language is an important part of communication which can constitute 50% or more of what we are communicating. If you wish to communicate well, then it makes sense to understand how you can (and cannot) use your body to say what you mean.
Body language comes in clusters of signals and postures, depending on the internal emotions and mental states. Recognizing a whole cluster is thus far more reliable than trying to interpret individual elements.

Aggressive body language: Showing physical threat.
Attentive body language: Showing real interest.
Bored body language: Just not being interested.
Closed body language: Many reasons are closed.
Deceptive body language: Seeking to cover up lying or other deception.
Defensive body language: Protecting self from attack.
Dominant body language: Dominating others.
Emotional body language: Identifying feelings.
Evaluating body language: Judging and deciding about something.
Greeting body language: Meeting rituals.
Open body language: Many reasons for being open.
Power body language: Demonstrating one's power.
Ready body language: Wanting to act and waiting for the trigger.
Relaxed body language: Comfortable and unstressed.
Romantic body language: Showing attraction to others.
Submissive body language: Showing you are prepared to give in.

Signals can be sent by the individual parts of the body. For me very interesting part is face, because face is so expressive and can say a lot of information about people, about their feelings, emotions and so on. There are some examples:

Anxiety - Eyes damp; eyebrows slightly pushed together; trembling lower lip; chin possibly wrinkled; head slightly tilted down.
Fear - Eyes wide, closed or pointing down; raised eyebrows; mouth open or corners turned down; chin pulled in; head down, white face.
Anger - Eyes wide and staring; eyebrows pulled down (especially in middle); wrinkled forehead; flared nostrils; mouth flattened or clenched teeth bared; jutting chin, red face.
Happiness - Mouth smiling (open or closed); possible laughter; crows-feet wrinkles at sides of sparkling eyes; slightly raised eyebrows; head level.
Sadness - Eyes cast down and possibly damp or tearful; head down; lips pinched; head down or to the side.
Envy - Eyes staring; mouth corners turned down; nose turned in sneer; chin jutting.
Desire - Eyes wide open with dilated pupils; slightly raised eyebrows; lips slightly parted or puckered or smiling; head tilted forward.
Interest - Steady gaze of eyes at item of interest (may be squinting); slightly raised eyebrows; lips slightly pressed together; head erect or pushed forward.
Boredom - Eyes looking away; face generally immobile; corners of mouth turned down or lips pulled to the side; head propped up with hand.
Surprise - Eyes wide open; eyebrows raised high; mouth dropped wide open with consequent lowered chin; head held back or tilted to side.
Relief - Eyebrows tilted outwards (lowered outer edges); mouth either tilted down or smiling; head tilted.
Disgust - Eyes and head turned away; nostrils flared; nose twisted in sneer; mouth closed, possibly with tongue protruding; chin jutting.
Shame - Eyes and head turned down; eyebrows held low; skin blushing red.
Pity - Eyes in extended gaze and possibly damp; eyebrows slightly pulled together in middle or downwards at edges; mouth turned down at corners; head tilted to side.

References:
http://changingminds.org/techniques/body/body_language.htm
http://en.wikipedia.org/wiki/Body_language