EdX is offering more than 140 Harvard courses to the public, among hundreds of other courses. According to Business Insider, "edX counts many of the world's top universities — including Berkeley, MIT, Cornell, Dartmouth, Princeton, Georgia Tech, and the University of Chicago — among its participating institutions."
If you are interested in learning about productivity and happiness, Yale is also offering its most popular course ever, "The Science of Well-Being," for free right now on Coursera.
Other organizations and companies are offering more focused training. For example, the Good Food Institute recently created the world's first college course on plant-based meat and is offering a self-paced six-week introductory course.
If you are overwhelmed by the number of options, ClassCentral.com can help you navigate them. Users can search by interest, subject, start date, and language. From there, the site will direct you to where the course is taught, where you can read more in-depth information about the course, professor, and institution.