Europe's Network of Patent Databases - Containing information on over 90 million patent documents from all over the world dating from the 19th centurty to today, Espacenet allows users to search patent publications, track progress of new technological advances, and monitor progress of competitors.
Google Patents - Google Patents searches, dating back to 1970, are run through the United States Patent Trademark Office (USPTO), the European Patent Office (EPO), and the Wrold Intellectual Property Organization (WIPO). An advanced search option is available.
ROMARIN - Search all international marks that are registered under WIPO's Madrid System by with this database. It includes marks that are active, pending, and recently expired.
Global Design Database - This database allows users to search through over 1.5 million industrial designs. It includes data that is registered under WIPO's Hague System or in participating national collections.
Free Patents Online - Search through US patents/patent applications, WIPO, European and Japanese patents all in one place.
Japan Platform for Patent Information (J-PlatPat) - Launched by the Japan Patent Office and the National Center for Industrial Property Information and Training, users can search via number, classficiation, or keywords to find Japanese patents. This site offers an English translation of patents.
STO's Internet Patent Search System - This website focuses on global/patent innovation quality and offers substaintial information including numerous links to studies on innovation and patents, a U.S. patent quality spreadsheet with data from 1984-2012, timelines, statistics, and patent caselaw material.