Nose roll turns can be used on all types of terrain but they're an especially great technique for hard snow, steeps, bumps and crud. Nose roll turns are really good for situations where you might feel like you're in over your head and you want to make your snowboard come around and turn on a dime.
Video: Snowboarding: How to Do a Nose Roll
Nose Roll Technique
As you're getting ready to start a turn, flex your knees with your weight even on both feet. Once the snowboard is loaded up and weighted, go ahead and unweight the tail end of board and rotate around your front foot, or the nose of the snowboard. This allows you to turn on a dime.
As you finish the turn, land low again. If you need to, let your board scoot underneath you to load the tail of the board so it doesn't chatter or side slip across the hill.