What! No mention of Hockey Night in Canada?
I agree with Corner Gas, North of 60, and The Nature of Things. I'd add:
This is Wonderland
DaVinci's Inquest (although I haven't watched much this year)
The Mercer Report
This Hour Has 22 Minutes
Diplomatic Immunity (TVO production, panel discussion of international politics)
and some years ago:
Lexx
Along with being slower paced, quirky and not as flashy as American TV, Canadian productions often deal with more controversial topics and in a fairly liberal manner. I doubt if any of the shows on my list would be accepted in the US except on some PBS stations. I've heard rumoured that popular export productions, such as DeGrassi Jr. High, need a lot of editing before being shown in the States. On the other hand, from what I've seen of Brit TV, they would probably be very acceptable in the UK, and Australia.
(One thing I love about British productions is the depth of their actors abilities. I don't think ours, Canadian or American, can touch them. Often a British actor will be in both dramatic and comedic series, and be completely believable in each.)