There are many criticisms of SOPA and PIPA (e.g. the ones at EFF, Gizmodo, and reddit), but let me focus on one: under the proposed law, linking to a website with infringing content is illegal.
Censorship aside, that presents a huge day-to-day operational problem for many law-abiding websites. For a blog like Neatorama, which has nearly 40,000 posts and over 311,000 comments, this means that we'd have to police every single comment to ensure that nobody links to a rogue site (and continuously checking that legitimate links in past comments haven't gone rogue), otherwise we'd be breaking the law. A gargantuan task, indeed.
I urge you to contact your members of Congress and ask them to vote against SOPA and PIPA: LinkUpdate #1 1/18/12: Sign the Petition or Call Your Representative and tell them to vote against SOPA and PIPA - Thanks for the suggestion, ray hahn! Update #2: Header on all Neatorama posts now links to the petition and call pages.