Actually, it's called "rolling" takeoff. If you are cleared to takeoff before you enter the runway, you may put some thrust still being on the taxyway until engines stabilize, then, when you are 45 degrees to align with the runway, you can apply slowly takeoff thrust, and that's good cause you enter the runway running and you brake the inertia. it's a good practice with a high takeoff weight, and also in any other condition. And it is used whenever you are cleared for takeoff before entering the runway, doesn't matter if it is in a congested or in an empty airport.
As it was stated before, tower may ask pilots to "enter into position and hold", normally if there is another aircraft on the runway, or clear the aircraft to takeoff if the runway is clear... no big deal!
Also, another interesting case is the "static" takeoff, done normally with max takeoff weight. You allpy takeoff trhust with the brakes on, then you slowly depress the brakes and the aircraft starts a fast run from zero.