In Canada, CFVO/30 went on the air as Ottawa-Hull's TVA affiliate in September 1974. The station was owned by a co-operative, and was the only such station in Canada. The station had a lot of financial problems and went off the air in March 1977. CFVO was probably best known for its "Cinerotique" pornographic movies on Friday nights, which reportedly drew higher ratings in its time slot than any other French or English station in Ottawa-Hull.
TVA service did not return to Ottawa-Hull until 1978 when current affiliate CHOT/40 went on the air. TVA programming aired on SRC affiliate CBOFT/9 in the interim.
A slightly longer-lasting station was CJSS/8 in Cornwall, Ontario, a CBC affiliate which lasted from 1958 to 1963. The station had financial problems, and then was bought by Ernie Bushnell who converted it to a repeater of CTV affiliate CJOH Ottawa. From a technical point of view Channel 8 never went off the air, and I've seen anecdotal evidence indicating the CJSS callsign was still in use into the early 1970s.
Aside from CJSS and the odd situation with CFVO, there haven't been many short-lived TV stations in Canada.