Chrome: Apps like Readability turn web pages into a format that focuses on making the text easy to read by stripping away distractions. Text Mode offers a different kind of distraction-free web browsing that retains the structure of the web page.
As you can see in the screenshot above, text is rendered in the same way -- just without colour. Images, however, become a diagonal striped pattern, so you can focus entirely on the written words. To activate Text Mode, you just click on the extension button. To turn it off, just click the button again.
The only very minor issue is that Text Mode doesn't work in Hi-DPI mode or retina displays. If you're looking for an alternative way to make web pages less distracting, all you need is Google Chrome and this free extension.