The
 following group are not for profit and allow free enrollment. (You may need 
to make a payment for a university or high school equivalency 
certificate.) Generally each course starts on a particular date and you 
are encouraged to keep up with the class by viewing the lectures and 
doing the course work each week. 
Future Learn - Mostly British-based universities.
EDX -
 another group of well-known universities, I
 have signed up for the "Science of Everyday Thinking" course, a fairly 
lightweight psychology course. 
Previously I have completed "Introduction to Biology (The 
Meaning of Life!)" and "Our Energetic Earth". The latter, from 
University 
of Toronto, was interesting but lightweight, with a talking head 
lecturer plus slides and some recommended texts. The former was the 
wonderful Generitcs, Biochemistry and Genomics course I mentioned. Live 
lectures and a gifted lecturer.
 Fantastic software tools in the homework (as you'd expect from MIT, I 
suppose).
Khan Academy has mostly
 pre-university courses, but they seem to be conducted in a very 
approachable way. Emphasis on mathematics. Self paced. I have viewed a 
biology and world history course accessed through this portal and 
it's a lot of fun! Also on YouTube: Crash Course Biology. Videos with a quirky approach that would 
appeal to teenagers, I think.
Academic Earth
 have pre-recorded mostly university lectures. I have just started one 
called Oceanography, which is recorded from the back of a darkened 
lecture hall with a computer-generated slides projected on a screen. 
It's just like being there, sometimes out of focus and all :-) I'm glad I
 didn't pay for that university course, but perhaps it will pick up.
Iversity
 is a German-based MOOC but they have a number of what appear to be good
 courses in English. I vill let you know vhat I zink of zem :-)
Saylor.org has
 a set of on-line courses that are contributed by experts and seem to 
consist mostly of self-paced directed readings of on-line materials with
 occasional viewing of videos. This is more of a traditional approach to
 a "correspondence course". It probably works well for people who like 
reading.
The following is a for-profit company but they
 allow you to do the courses for free and give you a certificate with an
 extra payment for "validation" i.e. university-equivalence. So basically the same results as far as the user is concerned.
 
 
