Firstly, you can access the mobile version of the website. Even though it was intended for mobile web browsers, you can access the mobile version of Wikipedia by entering http://m.wikipedia.org/ into your address bar. Secondly, you can access through apps on mobile devices – since they usually access content from the mobile version of the site (some even download them) they should be immune to the blackout.
Thirdly, you can disable JavaScript on your computer’s web browser (the blackout page is loaded with JavaScript). While this will make Wikipedia work, other websites that rely on it to function might not, so you’ll have to remember to switch it back on when you’re done Wiki-ing. Other methods include locating a cache of the website through Google; and accessing Wikipedia in a different language (since foreign versions of the website aren’t taking part in the protest).
Hopefully this helpful tip will ensure the blackout doesn’t inconvenience your day – though you should take a moment to find out more about SOPA in case you haven’t been clued in about it yet. After all, that’s what the whole blackout is about – raising awareness about what would happen if the law comes to pass.