Gilles Mischler built and designed Facebook's IT infrastructure from the ground up.

Employed by Facebook from: June 2005 - May 2010

Position at Facebook: SiteOps Engineer

Where he is now: After Facebook, Mischler went to Playdom. He was only there for a few weeks when the company was acquired by Disney for more than $700 million. Mischler then went to Nokia as a network engineer. Now he's a consultant for fast-growing companies.