United States Patent and Trademark Office Home Page -Who says the government never does anything right. This is a great web site, with a wealth of useful information. All U.S. Patents from 1976 to the present are available, including the drawings, in Adobe Acrobat™ format. The text is available in text file format and is easily searchable, using just about any browser (control "f").
Delphion Patent Server - In addition to US Patents, this site can provide the viewer with European patents.