I have recently become quite interested in adding to my repertoire of tools for working with overly active, difficult to focus, short attention span children in the context of teaching the martial arts.
Of course (and unfortunately), there is no magic bullet.
This page contains a series of links that I think may be valuable:
Positive Reinforcement, Not Humiliation is an opinion piece with specific examples of positive reinforcement to help behavior issues.
Drills and Concepts for Working With ADD/ADHD Children in the Dojo is, well, just what the title implies. (The advice is not specific to a type of martial arts.)
An Awesome Alternative to Drugs: Martial Arts practice as Treatment for AD/HD Children is academically formal advocacy piece on using martial arts as a treatment for AD/HD, not just how to deal with AD/HD in a martial arts setting. There's no origional research here but there are many citations and much impassioned reasoning.