I see what you're saying, but in this case slacktivism may be the best thing to do. The issue, from what I've understood, is that not enough people know about SOPA. And where do you best spread information? Yes, on the Internet.
People have tried -not- slacktivism, which is calling representatives. There's not enough of them. Try some slacktivism first to get peoples attention, then go for the big things.
Back in my facebook days, there were a lot of these 'awareness campaigns' on my wall, people changed profile pictures, posted some wierd messages, etc. After a gazillion of them, I just stopped caring and didn't even ask what another kind of ribbon means.
But that's not the point. The point is, awareness campaigns must have a call to action. Changing profile pictures make people feel comfortable that they 'did something to support' and in the end it doesn't matter. I'm not a US citizen, so it's up to you to decide what to do, but do something useful, not another fun game of replacing profile avatars so people think they're fighting for the cause while doing nothing.
True, I see a lot of these as well, and I don't care much either. This time however, they do have a "call to action", which is to call your representative. Now, I'm not a US-citizen either but from my understanding that's the best you can do as a normal person.
http://en.wikipedia.org/wiki/Armchair_warrior