• Derwent Innovations Index
  Provides access to more than 14,800,000 patents with links to cited and citing patents, cited articles, and full-text patent data sources. Access for students and employees at Aarhus University
• Esp@cnet 
  Free patent information on the internet
• Google Patents
  Patents and patent applications from all over the world
• USPTO Patents Database 
  Web site for searching, viewing, and analyzing patent documents. Free access to a wide variety of data collections and patent information
• Information (and links) on patents 
  Information on Europeen and US patents