Best Online Credit Check

freecreditreport.com
References :

http://www.annualcreditreport.com

This central site allows you to request a free credit file disclosure, commonly called a credit report, once every 12 months from each of the nationwide consumer credit reporting companies: Equifax, Experian and TransUnion.

AnnualCreditReport.com is the official site to help consumers to obtain their free credit report.
References :
AnnualCreditReport.com

https://www.annualcreditreport.com/cra/index.jsp

This is the site that gives you one free credit report from each of the three credit reporting agencies as required by federal law. There are no strings attached with this site. The best strategy, in my opinion, is to only get a report from one agency at a time, and spread the three request from each agency over the year. That way, you can check your credit report three times in a year for free without signing up from anything.

See the link from about.com in the source for more information.
References :
http://banking.about.com/od/loans/a/freecreditrpt.htm

if you are looking for the best credit report online site, check out this site

http://Credit-Report-Online-USA.com/

Here you can check your 3-in-1 Report from all three credit reporting agencies and your credit score rating.

Hope this help,
References :