V.W.
I don't have any first hand experience dealing with Asperger's, but if he is doing well in school other than the moodiness and attitude stuff, maybe you could consider a karate class for him.
My son's karate school (and all of them that I have heard about really) really stress and spend a pretty good amount of time on 'respect'. Both self respect and respect for others. They strive to work on self-control, both physically and emotionally (attitude is EVERYTHING in karate). It also is not a team sport, and all progress is really associated with your own personal improvements, not what everybody else is doing. I have seen the instructors at my son and daughter's school work really well with kids who have disciplinary issues and troubles caused by attitude at school.
I'm sure other moms here will be able to point you in the right direction as far as medical/neurological therapy interventions, but I wanted to put the 'karate' thing out there, too. He might really enjoy it, and the instructors and ALL the staff, really, at my kids' school are superb role models. I LOVE that my son has such an array of personalities and ages modeling good self control and respect for others. Some of the instructors are late teens, some are grand parents. Most are in their early 20's and really can relate to the kids in a way that moms can't. They are mostly guys, too. :)