I get a few visitors from Youtube and twitter, nothing from the other channels mentioned above. A poll could be a good idea!
Twitter woks for me because I am scheduling my tweets ahead of time in a predetermined rotation using tweet later.
It all depends. If you get a story on the first page of digg, then digg. Or if you have 10,000,000 friends on facebook, then facebook. Or if you have 25,000,0000 followers on twitter, then twitter. It all really depends. They are all good for getting traffic if used right though.