This Web site offers a fully searchable patents database as well as free access to the full text of the patents from U.S. patent 4,000,000 forward. The patent images are available in PDF and TIFF formats.
Each week FreshPatents.com lists the latest published U.S. patent applications under review by the USPTO. Innovative services include keyword monitoring, RSS/XML feeds, and browsing by location. This service is free, but registration is required.
Google Patents covers patents and patent applications from 17 patent offices, including the U.S. (back to 1790), European, China, Japan, Korea, WIPO, Germany, Russia, U.K., and France.
Enter a U.S. patent number and Pat2PDF will generate a free copy of the patent in PDF format.
This site provides access to the U.S. Patent Full-Text Database (a database of issued patents, full-text since 1976, full-page images since 1790) and the Patent Applications Database (a database of patent application published since March 15, 2001).
WikiPatents is a free U.S. patent database beginning with patent 3,930,271, and running through the most recent patents and patent applications. It includes a basic patent number search as well as an advanced search mode. In addition to providing both HTML and PDF versions of patents, WikiPatents features a wiki-like interface to review, rate, and discuss patents. Registration is required to access PDFs and use the wiki-like features.