The State of Florida has, within their local branch of the Health Department, has something called CARD (Center for Autistic Related Disorders). Through that, I was able to get my son in a peer behavior modification (for lack of a better term) class. All of the kids were preteens. They would put the kids through various scenerios requiring social skills and record the kids as they went through it. Then, they would watch the films back and talk about what could have been done differently. It was helpful for him and he was also able to socialize with other students with his mindset.
Those classes were offered free of charge regardless of income level. You could see if your state offers similar things.

The local children's hospital also offers peer classes for Asperger's kids, but I believe those cost some. Just a few things to possibly check out.

Temple Grandin, a leading expert on high level autism (she's Asperger's but the term didn't exist when she was diagnosed) has a number of lectures on YouTube. You may be able to find hers as well as some others; they may give you some ideas of things to try at home.

You could also get your son involved in some type of group activity outside of school. Some type of sports or scouting. You would be active with it with him so you could watch and see where he has difficulty and intervene if necessary. My son is in scouts and it has made a gigantic difference in his social skills. He doesn't always act what would be considered "appropriate" but he has become much more outgoing from the experience....plus it teaches good values to boot. You could even search for a troop of Aspie kids. I know they exist here and there.