One of the speed drills I recommend for football players is the 30-Yard Shuttle. It's a great drill because it develops both acceleration and deceleration, which are essential for football.
Acceleration is critical for bursting off the line and getting into the open field as quickly as possible. (See The Mechanics of Improving Acceleration.) Deceleration helps you slow down faster to make a cut, decreasing the time it takes to change direction and re-accelerate. (See Deceleration: The Missing Link in Speed Training.)
To enhance these abilities, you need to focus on short sprints like the 30-Yard Shuttle. Perform this drill two to three time per week during your speed workouts. Do it for four to six sets and rest for three minutes between sets.