I do plenty of things illegally and I've pirated a some music and movies but I am proud to say that I have never downloaded magic content illegally.
That being said, this thread actually incited me to go look around a little bit, and I will say that unless you really know what you're doing you will not find much magic available to pirate, and what you do find looks like it's lacking in the seed department, probably very slow goings.
And one last thing, steerpike brings up an interesting point with the economic value of pirating media. I do not think that money (or lack thereof) should be a good reason to download media. If you wanted something bad enough you would work hard for it and respect the creator by buying it. If you don't care about the creator you most likely pirate because it's convenient and free, not because you simply don't have, or could not get the money. We all love free!