Forbes has an excellent editorial up about the ESA's support of the Stop Online Piracy Act that does a great job of explaining - in simple English - how it could affect every day web sites who might not necessarily be engaged in anything but providing content.
The editorial cites an incident that happened to popular tech and culture blog Boing Boing. The site posted a picture of a Ralph Lauren ad for a news story. Lauren's PR and lawyers demanded that they take it down, but Boing Boing refused. That was pretty much the end of it under current "fair use" law in the U.S. But under SOPA, where the entertainment industry would have as much power as the government (the Forbes article describes them as deputy sheriffs), Boing Boing would be forced to take the picture down. Further, they could be blocked at the ISP and domain levels, their funding could be cut off, and anyone linking to the story in question could be forced to remove the link or face similar punishments.
It's a domino effect, where the accused has no due process - they either comply or face the consequences, and if they do want to fight it they have to go to court where they are basically already considered guilty until proven innocent. When people compare SOPA to legal mechanisms used in countries like China to censor, they aren't exaggerating...
At the very end of the article, the author urges ESA and groups like it to support bills like Daryl Issa's OPEN act; as they point out, the bill may not be perfect but it's better than SOPA or Protect IP. Fair Use is one of the issues that has not had a lot of discussion during the debate over SOPA, so I’m glad someone is finally talking about it. You can read "Why the ESA is Wrong to Support SOPA" by visiting the fine folks at Forbes.