The famous indie game competition is hosting a virtual game jam throughout the day, asking indie game developers (or anyone off from usual work) to make games inspired by the fight against SOPA. There are already a few submitted, and you can make and add your own, or see what other developers have done throughout the day. It's just a freeform jam, so there aren't any real prizes to be had, except that we all get some fun (or crazy, or hastily designed) indie games to play afterwards.
The #sopajam hashtag is being used to follow the conversation on Twitter, and at least one major indie developer has taken up the cause himself. Last time Notch jammed on a game it turned into a real Mojang release, so who knows what we'll get this time?