Empathy may be the most important skill to have, and one of the signs of an emotionally intelligent, empathetic person is his or her ability to accurately read others' facial expressions and body language. This quiz from University of California, Berkeley, not only gauges this skill, it also offers pointers on how to read people better.
The quiz shows you 20 photos of various people expressing a certain emotion, which you have to guess. Most of them are obvious (the wide-eyed look of surprise, for example), but some are a bit trickier, with some emotions only dissimilar to others by, say, the particular tilt of the head.
The explanations for each emotional expression can be helpful for you to further cultivate empathy.
Body Language Quiz [The Greater Good Science Center at University of California, Berkeley]