McAfee SiteAdvisor is a free tool that works with Internet Explorer. As you search or browse, SiteAdvisor's safety button changes color based on our test results to let you know if the website is Safe, needs Caution or needs Warning. More about it here. Their blog has also interesting articles like the one about clone detection.
Update. For some reasons the blog shows as not tested but it is if you check here: http://www.siteadvisor.com/sites/jtbworld.blogspot.com