this american GP has worked with adults and children with adhd for the last 14 or so years. he was diagnosed at the age of 40 shortly after both his sons were diagnosed as having adhd. he has written some excellent blog posts which can be found at Attentionality and a book for people diagnosed as adults.
I particularly like this post where he writes about his first experience of medication and what it taught him about adhd.
i think this man is a gem. and i can't remember his name - bums