Usually when this happens it's the job of the offended party to have the content removed, as you've probably seen on YouTube many times. These two bills would instead allow the entire site to be blocked.
Without user content portals like Scribd and YouTube, the Internet becomes just another mainstream media outlet, instead of the wild proving ground of ideas that allows regular people like us to find a large audience.
Please, if you live in the United States, do everything you can to prevent this.
- Educate yourself about how SOPA and PIPA work.
- Print and mail letters to your state's senators and representatives, urging them not to support this. Physical mail is harder to ignore than email. It piles up. You can find representatives' addresses here and senators' addresses here. Remember that PIPA is a Senate bill and SOPA is a House of Representatives bill.
- Call your senators and representatives on the phone and urge them not to support the bills. See above links for phone numbers or click here to get a quick list of representatives based on where you live.
If you want to blackout your own site, feel free to use any elements from this page.