I was trying to add Canadian holidays to my iCal, but all I found was the Apple version, which was missing Easter, St-Jean-Baptiste, and had the wrong Family Day, and a very old hint which didn't work anymore.
So I started with Apple's version, added the missing Holidays, fixed Family day, and published it myself. Feel free to comment about errors or omissions. I'll update this calendar directly, so everyone subscribed will get the updates.
Note: Valid until 2010.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20060122173523161