Marissa Mayer

July 17, 2012-onward: Yahoo gave interim CEO Ross Levinsohn the cold shoulder and instead opted for start power by naming Marissa Mayer, one of Google's top execs, as its next CEO.

The appointment of Mayer, 37, is a big coup for Yahoo. She joined Google in 1999 as employee No. 20 and has been Google's most prominent female executive, often speaking at big tech conferences about Google's products. She is known as the person responsible for the look and feel of Google's most popular products -- not just its main search home page, but Gmail, Google News, and Google Images.

More recently, she was put in charge of Google's maps and location services. All told, she was behind the launch of more than 100 Google products and features, according to Yahoo.

What's still unclear: How this dyed-in-the-wool Googler will fare in the Yahoo snakepit. Hopefully she'll have better luck than Carol Bartz.