If your trading gains are classed as income, not capital gains, and you make a decent amount from trading (at least equivalent to a healthy salaried job) then it might be worth it. CCRA recently gave a ruling that daytrading is a business like any other, removing some grey areas when it comes to incorporation.
Eventually it all evens out, but it's a good way to defer taxes at the lower corporate rate.
For example, say your personal rate is 38% and the corporate rate in your province is 18% and you make $200,000 from trading (classed as income, not cap gains or dividend income).
File and pay personally: 200,000 * .38 = $76,000 taxes. $124,000 left over
Trade in a corporation and pay yourself a $50,000 salary
50,000 * .38 = 19,000
150,000 * .18 = 27,000
total tax paid = 46,000 a savings of 30,000. Not really a savings, but a deferment. You will eventually pay it all out to yourself at a personal rate, but in the mean time, your account is bigger at the start of each tax year, so it can compound faster.