Copyscape

It is really hard to create unique content for your website. Some webmasters don't even take the time to do this. They simply copy your articles and upload them as it would be their own work. Copyscape is an online tool that helps you find duplicate content of your pages. You simply enter the URL of your site and it does the search and lists the pages that possibly stole your content. The free version displays only one result and you can sign up to a paid membership to see all those filthy sites.