Site advisor for Internet Explorer and Firefox.

[Coldfeet]

These days, even casual Web surfing can expose you to threats such as covert spyware installs and browser hijacks. This free and ingenious little Browser extension gives you a leg up online by alerting you to potentially hazardous Web sites. SiteAdvisor appears as an unobtrusive icon on the toolbar Whenever you visit a new site, the icon will display one of three colors: green means it's safe, yellow means it's iffy, and red indicates the existence of potential threats or annoyances. This site clean as the driven snow.
http://www.siteadvisor.com/download/ie.html