I thought maybe Toronto deserved its own thread, considering it's the largest city, and the Ontario list is getting quite long.
http://oja.emersonmedia.com/Research/Toronto-Jewish-City-Directories has online searchable city directories for 1924, 1925, 1926 and 1931 for Jewish individuals and for businesses operated by Jews.
http://www.toronto.ca/archives/photographs/index.htm Toronto City Archives has some photos online, among other things. This is where property assessment records are held, but need someone to go in person.
http://www.rootschat.com/links/0171d A selection of the historical photos owned by the Toronto Public Libraries are online.
http://www.torontopubliclibrary.ca "Ask a librarian" will do look-ups that don't take too much time. Extensive collection of city directories, phone books, and local history.
http://www.torontofamilyhistory.org/ Toronto branch of the Ontario Genealogical Society; many links and services. for a small fee, they will do a search of Toronto cemeteries which they have already indexed (info not yet online).
http://www.pagesofthepast.ca (Toronto Star newspaper archives, searchable)
http://www.torontosun.com (Toronto Sun newspaper archives. This paper only goes back to the 1970s.)
http://www.archive.org/search.php?query=toronto%20directories Old city directories online, approx 1900-1920.
http://www.mountpleasantgroupofcemeteries.ca/ These people own a substantial portion of the cemetery plots in Toronto. They will tell you by email if someone is buried with them, but they charge a lot of money for details to be sent to you.
www.catholic-cemeteries.com Roman Catholic cemeteries in the Archdiocese of Toronto (which also covers some areas outside of the city proper.)
http://www.rootsweb.ancestry.com/~obituary/ Toronto has been covered on this obituary index site for many years, and it covers some of the gap between what is available at pagesofthepast and
www.thestar.com .
http://www.archtoronto.org/arch_offices/archives.html Archives of the Roman Catholic Archdiocese of Toronto.
http://www.toronto.anglican.ca Anglican diocese of Toronto has an Archives department.
http://www.archive.org/details/landmarkstoronto04robeuoft Digitized version of important book on Toronto history, published 1904.
http://www.benjaminsparkmemorialchapel.ca/Default.aspx This is the Jewish Funeral Home, and carries listings online going back over 40 years, often including obituaries.