I'm not sure if this will help, but I know NAQ (North American Quotations) is a big player in the data market and they are based in Canada. I do not know if they have brokerage functions, though. Perhaps you can check their site: http://www.naq.com
really the only reason to trade Canadian stocks (considering how thin and mostly low quality the market is and how high the brokerage fees are) is because RRSP rules for investments require Canadian content.
I agree with trader42 about the liquidity...it often sucks, but keep your eye on the gold price. If it starts to move the gold and exploration stocks can become very liquid very fast.
um, the rules allow you to trade all you want in eligible foreign content (US stocks). at the end of each month your plan administrator will add up the foreign amount over 30% (cost basis) and levy a 1% penalty, payable at end of year. it is a cost of doing this business, and becasue of the way they calculate, you can go out of positions for a day at the end of each month and may not pay anything. you can also buy labour funds to increase the amount of foreign content up to 50%.