Whenever I teach rudimentary-level college math courses (which is just about all the time these days), I send my students to the Khan Academy website and encourage them to spend as much time there as they can.
There is some good stuff there; I've learned a few things myself from some of the other courses.
I have no experience with the bigger places, and don't know much about how accepted the certificates are in business or in education. I would suspect that most of the universities will still circle the wagons in defense against MOOC certificates as a substitute for course credit for as long as they can (though eventually someone will relent, that someone will be big enough, and there will be a shift).