I can't help agree with a poster above, who recommended the Ken Robinson video.
I also wanted to add that I think the way that our modern education system works has a lot to do with parents seeking a diagnosis for little Bobby "who just can't sit still".
I used to work in the environmental education field for quite a few years. I can say that I loved to have kids with "ADHD" in my group, because they were the ones turning over rocks and logs and activity searching for things. What is seen as a detriment in one setting, seemed to be an advantage in another setting.
An interesting thing to note is often how I would find out about their conditions. Since I did do some work at overnight facilities, I would sometimes would be told ahead of time medications and conditions a child had. But most of the time, I found out about it by a teacher saying something like: You know, so-and-so has a ADD/ADHD and he is just doing SO well out here.