Facebook's COO seems to be the popular choice these days for any CEO opening. Sandberg has a strong resume, having served as Google's vice president of Global Online Sales and Operations from 2001 to 2007 before leaving for Facebook. Prior to Google, she served as the chief of staff for the U.S. Treasury Department during the Clinton administration. Sandberg is also a member of Walt Disney Company's board of directors. But she's a true outsider, having never worked at Microsoft. Will Gates and company go with a brand-new face?