This extension/plugin for IE or FF may be of use for those interested in what sites they visit...

SiteAdvisor helps protect you from all kinds of Web-based security threats including spyware, adware, spam, viruses, browser-based attacks, phishing, online fraud and identity theft.

Our automated testers continually patrol the Web to browse sites, download files, and sign-up for things with e-mail addresses. As you search, browse, download or register online, SiteAdvisor's safety ratings help you stay safe and in control.
Might be useful on PC's where users are online, or just another measure of how to protect the user from malicious websites, at least it can be educational.....

Siteadvisor

Gives AO a clean bill of health....