U.S. PatentAndTrademarkOffice, where good patents go to die.
The US PTO Web Patent databases Patent Grants and Patent Applications http://www.uspto.gov/patft/index.html contain images of all US patents from the current week back to 1790 and the full text of patent applications published since March 15, 2001.
The Delphion Web site has international patent information (European patents - applications and issued, Abstracts of Japanese Patents, World Intellectual Property Organization publications) as well as the images of full text U.S. Patents from 1974 to the present.