An early Christmas present from the WIPO:
PatentScope now includes the Canadian national collection from ~1920 forward. No PDFs yet, it appears, but full text (based on OCR) is available for some patents. A few pre-1970s patents have IPC codes, so keyword searching may be required for some types of searches. This gives researchers another option for searching Canadian patents from the early 20th century forward.
Other national collections to be added in the next few months include the Eurasian Patent Office, Germany, and UK.