Google Chrome (browser and OS) has some great built-in accessibility features, as well as some excellent extensions that add accessibility features.
Google just released a new one that is very useful for people with vision issues, especially with colors. Color Enhancer is an extension that allows the user to easily select a color filter that improves color perception. It's very easy to use and works nicely. I have a mild red-green color deficiency and this helped me with some websites.
Click on the extension and follow the directions. It's that simple.
Google Accessibility Features in Chrome (OS and Browser)