I'm not techie enough to black out my website, nor do I have enough time. But I stand in support of those who are blacking out their sites in order to protest the SOPA / PIPA laws making their way through Congress. From what I gather, these bills will shut down sites large and small at the faintest whiff of copyright infringement, putting the blame on the site, not the poster.
Why is that a problem?
Say someone comes here to my blog and posts a link to a pirate site. By that link existing on my page, my site can be shut down and I am held responsible for promoting copyright infringement.
Youtube, Google, Craigslist, Reddit, any site where there is user submitted content is in danger if these laws get passed. Hell, any site where comments are allowed are in danger.
Check out these sites for more information.
Wiki explains the Blackout