Any airline that uses 727s, 747 classics, 707s (Saha only I'm afraid), DC-10s, L-1011s, A300 (non -600), or almost every Russian type that isn't brand new.
Interestingly, some newer Russian a/c still require a flight engineer. I believe Aeroflot has them on their Il-96s, despite it being a relatively modern aircraft.
[Edited 2011-03-30 15:35:04]
You know nothing Jon Snow