Aerospaceweb has a really neat article about the 8 largest helicopters in the world. This one above is the Soviet's Mil Mi-26 which is only the second largest: it can carry payloads up to 44,000 lb (20,000 kg). In the photo above, the helicopter is recovering an American CH-47 Chinook.
http://www.aerospaceweb.org/question/helicopters/q0284.shtml