On my Demon Hunter, I used to kite, turn around, and then spam Nether Tentacles. This did a ton of damage: all the monsters were now in a line so it would pass through them and do damage to all of them.
As of 1.0.3, this is now nerfed as nether tentacles will now only damage the same monster once per shot. Instead of Nether Tentacles, is there a better skill that I should be using for a kiting / class canon build.