Trying going to this link:
http://home.disney.go.com/music/
Maybe there will be something there that is appropriate for the 6 year old age range..it is the Disney website.
My daughter is the same age as your son, and she takes hip-hop dance classes at our local YMCA. Maybe your son would enjoy that too?
It's hard to find "music" for this age, which does NOT contain references to sex/kissing/dating/violence/cuss words etc. because the music is created by the pre-teen/teen/adult majority. But I"m sure there must be some for the young children... I know, try going to http://www.noggin.com/search.php?searchterm=music and they might have music too for this age.
All the best,
Susan