Yes. usually I use copyscape. But I have exceeded the number of checks for one domain and I do not have a premium account.
Here are a few sources for you: http://www.articlechecker.com/ http://blogoscoped.com/quotefinder/ http://doccop.com/index.html http://turnitin.com/ http://www.ithenticate.com/ http://www.scanmyessay.com/turnitin.php http://www.plagiarismchecker.com/help-teachers.php http://www.plagiarismdetect.com/ http://www.dustball.com/cs/plagiarism.checker/ http://plagiarisma.net/ http://www.plagiarismsoftware.net/ http://www.checkforplagiarism.net/signup.html http://www.canexus.com/eve/index.shtml
If I had enough money to get a premium account than I would have at first get a premium membership in this forum.
Below list of online duplicate content checker tools http://www.virante.com/seo-tools/duplicate-content http://www.webconfs.com/similar-page-checker.php http://www.dupefreepro.com/ http://www.plagium.com/ http://www.duplichecker.com/ http://www.articlechecker.com/ http://plagiarisma.net/ http://www.plagiarismchecker.com/ http://dupecop.com/ http://copyrightspot.com/ http://www.copygator.com/ Above all tools helps you to find duplicate contents or pages, but copyscape is the better than of other online tools.
CopyScape alternative http://www.plagspotter.com/ is pretty good as well, even though service is still in beta.
I believe a copyscape acct is $5 for 100 uses up to 2000 words, that is .05cents per use. If an article or up to 3-4 articles are not worth .05 to check they are not worth...._ not even worth my time to respond to this thread..