President Obama is unlikely to veto SOPA, if it passes, because he gets millions in contributions from Hollywood. See this page.
Does your congressman support or oppose SOPA?
Will Google, Facebook, and Twitter go offline to protest SOPA? This page says that they are discussing it.
If you want to boycott companies that support SOPA, install this Android app on your cellphone and scan bar-codes at the store.
Stop SOPA! Save Usenet!