EDGAR System of SEC for regulatory company information

Primary tabs

usa
economy
sec20f
Examples: 
sec20f Rio Tinto
search for a company with 20-F annual reports
URL: 
http://www.sec.gov/cgi-bin/browse-edgar?company={%company name}&CIK=&filenum=&State=&SIC=&owner=include&action=getcompany&type=20-F