Speed

Do any of you guys work with trainig your players on how to run faster? I've always heard that there are 2 things in baseball you cannot teach-You cannot teach speed and you cannot teach an arm. Either they have it or they don't. Technically, this may be correct, but I tend to disagree. You will not put a kid past his physical potential, but you can go a long way towards reaching that potential.

I've heard lots of drills and discussions on throwing, but what about running? What do you guys do to address this? I was thinking of buying the parachute and/or the elastic harness to help increase running speed. Any thoughts?