This is just a guess, but I would imagine that most of the top universities would only offer online courses for no credit, just enrichment, and/or have some online courses that would be part of a residency degree. Your best bet in terms of researching this further would be to go to the websites of the individual schools that interest you and look up their offerings under “distance education” or “online courses.” I am in education at a community college and that is the way we offer them.