Hi, Have you discussed this concern with your son's pediatrician? If not, please do. Your son's doctor can test to see if your son is lactose intolerant, or if there are any other related health issues involved in your son's refusal to drink milk.
Our daughter isn't really a big fan of milk either. When she was a toddler and we were particularly concerned about her lack of milk consumption (post-nursing), we tried putting a bit of chocolate syrup in it -- which she loved and her pediatrician ok'd if in moderation (our daughter has been skinny her whole life, so it was more a dental issue that we had to be cognizant of with the addition of the chocolate). We also blended milk with frozen strawberries, another favorite of hers. She also really enjoyed macaroni and cheese, which was another way she got her daily dose of calcium. Now that she's older (in second grade), she still doesn't like drinking a glass of plain milk, but she does consume it through bowls of cereal, hot cocoa, smoothies and other food items that contain milk (such as creamy pasta sauce or Indonesian dishes her daddy makes).
The main point is that your son consumes the recommended daily dose of calcium -- whether through drinking milk or eating it.
Here's a website for those with milk allergies that lists the calcium doses for alternative sources to milk (as well as daily recommendations for calcium per age group):
http://milkallergycompanion.blogspot.com/2009/02/alternative-sources-of-calcium-with.html
Here's a resource on Education.com that you may also find helpful:
http://www.education.com/topic/kids-recipes/
Good luck -- and please do include your son's pediatrician in this discussion.