Queen's University engineering librarian Michael White runs The Patent Librarian's Notebook, a very important resource for anyone interested in finding and making sense of patent information.
Canadian Patents Database (CIPO)
The Canadian Patents Database, which is maintained by the Canadian Intellectual Property Office, contains more than two million Canadian patents and published applications from 1869 to the present. Full-text images are available from 1920 forward. Recent improvements include a few aesthetic changes to the search interface and the inclusion of a representative drawing (if available) displayed in the bibliographic record. In addition, as of January 29, 2010, abstracts in both English and French are available for applications filed under the PCT. (Approximately 75 percent of patent applications received by the CIPO are filed via the PCT system.)
The other databases he covers include PatentScope (WIPO), Esp@cenet (EPO), USPTO, Patent Lens, FreePatentsOnline, Boliven Patents, PatSnap and Intellogist. He also discusses International Patent Classification (IPC) and IP5 Initiatives.
A year or two ago, I attended a day-long workshop on patent searching that Micheal lead and it was well worth it. If you get a similar chance -- take it!