This is an interesting article on lying and what liars tend to do. According to the article when people lie they tend to say certain things, do certain things, show different facial expressions, and make certain gestures. One example of what a liar might do is place an object (often something small like a coffee cup) between himself/herself and the person they are talking to. Of course if someone presents these "symptoms" of lying, it doesn't necessarily mean they are lying. An interesting thing about this article is to try to use the information to detect when others are lying.

http://www.blifaloo.com/info/lies.php