From Stanford comes an interesting paper about how users perceive the credibility of a web site. Over 2,500 people evaluated the credibility of two sites dealing with a similar topic.

An exerpt:
"...the average consumer paid far more attention to the superficial aspects of a site, such as visual cues, than to its content. For example, nearly half of all consumers ... assessed the credibility of sites based in part on the appeal of the overall visual design of a site, including layout, typography, font size and color schemes."