Date: 2/20/2013
Why: Usability, Functionality 

Despite what you may think, is still one of the most visited websites in the world. More than 100 million people visit Yahoo!'s homepage each day. And you thought it was washed it up? Even though her stated mission was to improve the company's mobile offerings, Marissa Mayer oversaw a complete overhaul of the company's most valuable property. Users are now able to login to the site using their Yahoo! or Facebook account. One of the main new features is the infinite scroll of personalized stories and photos that change depending on the user's taste.