I'm sure someone is already doing this but just in case...
How about a browser plug-in that subscribed to a public list of sites of people and companies that support SOPA and black them out.
Obviously it would be a voluntary thing to install such a plug-in. I would run it. I'd like to know.
Add to the list all Congress people who vote in favor of SOPA. Esp the pages where you donate money to them or volunteer to work for their campaigns.
While you're at it block pages on commerce sites where their products are for sale. No Internet revenue for companies who back SOPA.