Equifax enables you to request your credit report online -- their "Sentinel" credit monitoring service makes it easy for you to keep an eye on your credit.
Experian is one of the major credit reporting services and lets you order your credit report online for a small fee. They also offer other financial services around the globe.
TransUnion not only lets you order your credit report online, but also provides consumers with extensive information about their rights under the Fair Credit Reporting Act.
Yahoo! Finance allows you to order your credit report online (from Experian) -- or you may choose a package containing reports from all three credit reporting services.