[rpeden]

I'm not sure if you'd count IBM, but they have their Toronto Software Lab here. It's technically in Markham now, but if it were on the south side of Steeles instead of the north side, it would be in Toronto proper. AMD also still has a large office in Markham in what used to be ATI headquarters.

I've seen a few articles about Apple hiring developers in Toronto, so there's that too.

Maybe Waterloo is a bit too far away to count, but Google has a fairly big engineering office there.