The general term you looking for is integrated math. This is an alternative curriculum that is taught in the US, just less frequently than the traditional Algebra 1, geometry, ect.
What are you trying to get out of his taking higher math? Are you looking for classes that give your son credit or are you just trying to challenge him or prepare him for math completions? I ask this because if you don't care about credit classes than there is a lot more out there than Standford and John Hopkins. I don't have enough experience to recommend either but I am sure there are others here who can tell you their experiences.
Have you looked at Khan Academy (
https://www.khanacademy.org/ )or Aleks (
http://www.aleks.com/) ? Khan Academy is free, and I know Aleks has integrated math classes. I wouldn't do either instead of a course but they can work well for supplemental. Another option that many people here like is AOPS - Art of Problem Solving (
http://www.artofproblemsolving.com/). They have books as well as online classes. One advantage to their work is they are specifically geared towards higher critical thinking type classes not just meeting curriculum goals.