New Super Mario Bros. Glitches

Infinite 1-up
In world 1-4, go forward until you get to the red turtle. Jump on it's head, then pick it up. Make sure that you don't hit any Goomba's afterward, and still go fast. When you get to the part right before the staircase, make sure you cannot see the gold pipe, and throw the shell. It should keep hitting the walls and killing the Goomba's, soon you'll start getting 1-ups.

*Note: This may take a couple try's.*