[charlesdm]

Directors of Canadian companies who are living abroad is probably one example.

Also, people who, say, commute from CA to the US on a daily basis will generally be exempt from Canadian taxes because the work is performed in the US (just an example, I have no idea whether you can commute from CA -> US on a daily basis)

[seanmcdirmid]

Well, I was "taxed" on my Chinese income, but never paid a dime. Foreign tax credits and foreign income exclusions mean most of us pay nothing (well, we pay Chinese taxes, just not US taxes).