Although SOPA has been pushed to the backburner for the time being, it's not dead and we should remain vigilant in our opposition. Not only that, but SOPA is not the only legislation on the table that threatens the internet that we know and love. The Protect IP Act (PIPA) still sits in the Senate, and as a cousin to SOPA still has the ability to wreak havoc on the interwebs.
Reddit cofounder Alexis Ohanian has been a firm opponent of SOPA and PIPA since the beginning, and has taken to YouTube and social media outlets to protest what he calls internet-killing legislation.
Today, in a Google+ post, Ohanian explains that he'll be writing sympathy cards to his Senators "mourning the death of the Internet because they supported Protect IP."
Ohanian has also issued another video where he discusses the dangers of SOPA and PIPA:
He encourages us to check to see if our Senators support PIPA, and if they do, join in the letter writing. "Dear ______, I'm sorry for the loss of the free internet, which was killed by your uninformed and shortsighted support of the PIPA." Something like that, I assume.
Of course, you can also write letters to your Senator even if they oppose PIPA, in order to hammer home the need for them to convince their colleagues to switch teams.