I made an extension for Opera browser, based on the existing Google Chrome No SOPA extension, that will alert you when you visit a website owned or associated with the Stop Online Piracy Act legislation.
Pro-tip: Save the file to your computer first, then open it.
Self-promo-tip: Check out Game ID.
How it works
If you're on a 'bad' website, you will see a red bar along the bottom of your screen. The list of bad websites is currently stored locally on your machine. This means the list will not update until you update the extension. This transition will be made smoother should the widget be submitted to the Opera Extensions catalogue.
Follow @coxy on Twitter for future updates.
If you wish to give thanks for this extension, use Flattr.