The Power of Faces in User Experience
All of your design decisions about content, button location, fold awareness, navigation issues, and nearly anything else concerning your effort to provide a great Web site user experience can be significantly undermined if you fail to consider the impact that images of people have on your content.
The reckless addition of images of faces or poorly thought out reasons for including a picture of a person on a Web page can dramatically influence the impact of its content. If an image does not appear to relate directly to your content, your site design looks lazy, incomplete, and inadequately thought through.
A great story by James Coston on the impact of faces in User Experience.