what are the best ways/drills to try and help a kid develop better lateral quickness and speed?

Those are innate qualities that are controlled by your genes. We all have a certain potential. Your job is to come as close to your potential as possible.

Both of those issues are related to conditioning, strength and experience. You can't rush experience, but you can improve your strength and conditioning.

Experience is important because it allows you to anticipate. Strength and conditioning improve your flexibility and stamina which will enable your body to react with more immediacy over a longer period of time. Anything you can do to improve your strength and conditioning will help your quickness.

More importantly, learning how to take more direct angles, getting lower and more athletic in your stance when you play, better technique in your skills with also allow you to become dramatically quicker.

Along with everything Don said, I really like the mirror drill. You can view it here: http://www.youtube.com/watch?v=qjSzGMxaw4Y

Another side note, I believe that coaches sometimes screw up the way kids move. I used to tell my players, "Don't cross your feet on defense!" Now, I encourage it. I encourage the crossover step to stay in front of the defense. Watch a North Carolina game some time. You'll see their guards move like this all of the time. There are hundreds of defenders that are great at doing this in the NBA, but Kirk Hinrich of the Bulls always pops into my head when I think of the movement.

With that being said, if you see a player moving in a manner that will lead to an injury down the road or if they have terrible movement mechanics and are slow, you'll probably need to jump in and teach them the proper stance, stopping mechanics, and acceleration mechanics.

All this is good stuff. Another way to increase speed is anticipation. Of course physical development is great and something that should be done. But you can double the speed of your defense almost overnight by following the advice in this article:
http://www.breakthroughbasketball.com/d ... kness.html

I don't know if this can help but we use the agility ladder.. You can search the net for specific drills..