We brought the Home page design in line with that of the new Channels and Sections, while the underlying tech remains the same for now.

FORBES: The new Forbes.com: What's in it for you?

The company regularly tests its search system, what the home page looks like, overall site design as well as product pricing.

BBC: Amazon's old customers 'pay more'

Amazon spokeswoman Patty Smith said the price differences on certain DVDs are the result of tests that the company performs to re-evaluate various aspects of its Web site, such as the navigation system, what the home page looks like, overall site design and product pricing.

CNN: Testing reveals varied DVD prices on Amazon

SumbleUpon has revamped the design of the site and particularly its home page to focus on a visual experience with larges tiles of images.

FORBES: StumbleUpon Rebrands, Launches Brand Channels

Previously, the news feed occupied less than 40% of the real estate on the Facebook home page, according to Julie Zhuo, Facebook's director of design.

CNN: Facebook revamps site, tweaks mobile apps