Marissa Mayer made headlines last summer when she took the top job at Yahoo, becoming the youngest Fortune 500 CEO in history. She didn't land that gig simply because of her business acumen; Mayer has serious technology chops. She graduated with honors with a bachelor's in symbolic systems and a master's in computer science. She joined Google in 1999 as the company's first female engineer. There, she donned an array of hats as an engineer, a designer, a product manager, and in her final years, vice president of search products and user experience and vice president of local, maps, and location services.