[reg45]

The Russian Kamov helicopters typically have two main rotors that go in opposite directions.

This has several advantages:
1. The tail rotor can be eliminated.
2. The main rotors can be shorter.
3. The top speed can be higher.
4. The landing and takeoff footprints will be smaller.

[wetphoenix]

http://www.youtube.com/watch?v=cuceTxUSAR4

It is a very ancient design actually and it is much easier to handle than conventional chopper. This one, powered by a couple radial engines, was very popular in 2nd world at the time. There were people who have never seen an automobile but could easily operate this type.