Real (ok, "real") mindreaders also have some tricks up their sleeves, low-tech but still useful. Some of the tricks work so well that the "mindreaders" unconsciously trick themselves into believing in their own powers.

The art of "cold reading" is a fascinating read:

http://www.randi.org/library/coldreading/

Btw, I see your facebook profile in my crystal ball: http://www.facebook.com/profile.php?=7432645066541