"This type of thing doesn’t happen because companies typically don’t want to put their users in that position. The difference is that these bills so fundamentally change the way the Internet works. People need to understand the effect this special-interest legislation will have on those who use the Internet." --Time.com
This article debates whether or not these sites should go completely offline when the time comes, or be replaced with a screen explaining why they are down, what they are protesting, etc. Me, being a little extreme, think that they should just be completely down. "Internet explorer cannot find the page you are looking for" should show up. And yes, I realize I just implied that anyone uses internet explorer in 2012. Will it spark more outrage? Probably. Will it confuse people who don't know about the blackout? Definitely.
People, on this day, will go to log into their facebooks first thing in the morning (like 48% of 20-30 year olds, true story), and they will see that it is down, they will wonder why, and they will go to google it, but nope, Google's down.
This will be a very boring day but it is well worth the outrage and media coverage it will receive. I wish I could tell you who to write to encourage these sites to do this, as I fully support the idea. Will keep you all updated if I find anything.
Read the full article here
[EDIT: It is also important to let people know that this bill will not do anything to stop online piracy, but will only inconvenience everyday users. It does not support IP blocking, which means that online pirates will still be able to access the sites they want to. More on this article I didn't read because I basically just summed it up: More here...]