Contributed by Rivalremi
Gabe Newell served as a producer for the first three versions of Windows (Windows 1.0, Windows 2.0 and Windows 2.1x) before going on and founding Valve.
Contributed by ORWELL6
VALVe has a working sentry from Team Fortress 2 and a working turret from Portal in their lobby. Both were contributed by WETA Workshop.