SiteAdvisor was founded by a group of MIT engineers who realized there was a gaping hole in existing Web security products. While traditional security companies had gotten relatively good at addressing technical threats like viruses, they were failing to prevent a new breed of "social engineering" tricks -- scams that trick users into downloading malicious software or signing up at Web sites that send unwanted e-mail or steal personal information.

SiteAdvisor’s approach comes at a time when computer threats are shifting from technical attacks like viruses to economically motivated attacks like adware, spam, and phishing. An estimated 61% of all computers are infected with at least one piece of adware or spyware, according to The National Cyber Security Alliance and America Online (12/05). Jupiter Research (2/06) reports that the average consumer received 3,253 pieces of spam in 2005. “Phishing