Run Very Fast While Sneaking:

You have to have the One-Handed perk that allows you to attack while sprinting and the perk that lets you do a roll while crouching. To do this you have to: 1. Crouch 2. Forward roll 3. Immediately after roll rapidly TAP the right attack button. You should be standing and running very fast but will still be "sneaking". This works because in a small frame of time when you roll you are considered standing. This allows you to do the sprinting attack while crouched.