Census of 1851 -- Canada East, Canada West, New Brunswick, and Nova Scotia This site, launched in 2006, offers page images for the four provinces of New Brunswick, Nova Scotia, and the modern-day Quebec and Ontario (where the census was actually taken in 1852). "This tool allows researchers to search by geographic location only. As this is not a nominally-indexed database, it is not searchable by family name." An nominal index at Automated Genealogy is in the "proof-of-concept" stage, but see below for a complete index.
Census of Canada, 1901 (at Collections Canada) ArchiviaNet provides digitized images of the original census returns, which record age, nationality, religion, profession, income, education, and other data for every resident of 31 March 1901. The site also contains maps of census districts. The only method of access currently available is browsing by geographic location; it is not searchable by personal name. However, a complete, searchable trasncription is available free online at Automated Genealogy.
Census of the Northwest Provinces, 1906 At ArchiviaNet: In order to track the high rates of population growth in western Canada, the Canadian government called for a special census of the prairie provinces (Manitoba, and the two newly created provinces of Saskatchewan and Alberta) in 1906. This site provides digitized images of original census returns, which record the names of family members, their gender, marital status, year of immigration to Canada, post-office address, etc. Again, the only method of access currently available is browsing by geographic location. Two separate transcriptions projects are underway for this census. Automated Genealogy's index for Manitoba, Saskatchewan, and Alberta is described as "essentially complete" as of March 2008. The Alberta Family Histories Society is publishing a more complete transcription in PDF, searchable on their site, which already covers substantial parts of Manitoba, Saskatchewan, and Alberta.