SiteAdvisor, developed my MIT students, is a huge database of websites that either have executables with spyware/adware or start spamming you with e-mail once you give them yours.
McAfee today announced that it had acquired SiteAdvisor to improve its online security offerings. Just like the US Homeland Security National Threat level color codes, SiteAdvisor browser plug-in places a "safe," "caution" or "warning" label whenever a user visits a Web site.
When a user searches through Google, Yahoo or MSN, SiteAdvisor displays the safety rating next to the search result. Additionally, as users browse the internet, a button on the toolbar would change color based on that site's security rating.
SiteAdvisor also hosts a Site Report page that documents the results of every test on every Web site. Here's a sample SiteAdvisor report on Google, Microsoft and Yahoo.
SiteAdvisor | McAfee Press Release | BetaNews