The logical successor had been Steven Sinofsky, head of Microsoft's Windows unit. Sinofsky left the company late last year, after the launch of Windows 8 was poorly received by users, the media and the tech community, leaving Microsoft without an obvious successor to Ballmer.
It's highly unlikely that Microsoft co-founder Bill Gates will return to the company as CEO, as Gates is heavily involved in ridding the world of disease and making it a better place.
I've suggested that the man who built Lotus Notes, Ray Ozzie, return to Microsoft, where he was Chief Technical Officer and Chief Software Architect between 2005 and 2010. Ozzie is currently running a startup named Talko.Former Apple (AAPL) executive Scott Forstall is another name being mentioned in the Twittersphere, as the man largely responsible for building iOS has his non-compete agreement expiring in a few months, after he was ousted from Apple late in 2012. There are several other names being thrown out, including some internal candidates, and some external candidates, including Microsoft COO Kevin Turner, Tony Bates from Skype, and even former Microsoft executive and current Nokia (NOK) CEO Stephen Elop. TheStreet wants to know who you think should replace Ballmer.