Reading Glasses for Google Chrome dims out everything but what you want to read
There are a ton of add-ons that dim the screen while you're watching a video or playing a Flash game. Heck, some Web sites even have this functionality built right in, no add-on required.
Reading Glasses for Chrome does the same, but for text. As you can see in the screenshot, with Reading Glasses, only the post text is dark, while all other page elements are grayed out. This is accomplished by highlighting some of the text of the post, and clicking the "glasses" icon which appears next to the address bar once the add-on is installed.
I wish the add-on could make the page background dark and the text light. Also, it would be nice if it could make the text a tad larger. Then again – this is what Readability is for. Then again, Reading Glasses is a bit more lightweight and it doesn't impact the site's look-and-feel at all, except for fading it out a bit.